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TB hashing improvements 

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Merge remote-tracking branch 'remotes/rth/tags/pull-tcg-20160611' into staging

TB hashing improvements

# gpg: Signature made Sun 12 Jun 2016 01:12:50 BST
# gpg:                using RSA key 0xAD1270CC4DD0279B
# gpg: Good signature from "Richard Henderson <rth7680@gmail.com>"
# gpg:                 aka "Richard Henderson <rth@redhat.com>"
# gpg:                 aka "Richard Henderson <rth@twiddle.net>"
# Primary key fingerprint: 9CB1 8DDA F8E8 49AD 2AFC  16A4 AD12 70CC 4DD0 279B

* remotes/rth/tags/pull-tcg-20160611:
  translate-all: add tb hash bucket info to 'info jit' dump
  tb hash: track translated blocks with qht
  qht: add test-qht-par to invoke qht-bench from 'check' target
  qht: add qht-bench, a performance benchmark
  qht: add test program
  qht: QEMU's fast, resizable and scalable Hash Table
  qdist: add test program
  qdist: add module to represent frequency distributions of data
  tb hash: hash phys_pc, pc, and flags with xxhash
  exec: add tb_hash_func5, derived from xxhash
  qemu-thread: add simple test-and-set spinlock
  include/processor.h: define cpu_relax()
  seqlock: rename write_lock/unlock to write_begin/end
  seqlock: remove optional mutex
  compiler.h: add QEMU_ALIGNED() to enforce struct alignment

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Peter Maydell 2016-06-13 10:12:44 +01:00
parent a93c1bdf0b 329844d4bc
commit da2fdd0bd1
22 changed files with 2892 additions and 131 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

90
cpu-exec.c
View File

@ -225,57 +225,57 @@ static void cpu_exec_nocache(CPUState *cpu, int max_cycles,
}
#endif
struct tb_desc {
target_ulong pc;
target_ulong cs_base;
CPUArchState *env;
tb_page_addr_t phys_page1;
uint32_t flags;
};
static bool tb_cmp(const void *p, const void *d)
{
const TranslationBlock *tb = p;
const struct tb_desc *desc = d;
if (tb->pc == desc->pc &&
tb->page_addr[0] == desc->phys_page1 &&
tb->cs_base == desc->cs_base &&
tb->flags == desc->flags) {
/* check next page if needed */
if (tb->page_addr[1] == -1) {
return true;
} else {
tb_page_addr_t phys_page2;
target_ulong virt_page2;
virt_page2 = (desc->pc & TARGET_PAGE_MASK) + TARGET_PAGE_SIZE;
phys_page2 = get_page_addr_code(desc->env, virt_page2);
if (tb->page_addr[1] == phys_page2) {
return true;
}
}
}
return false;
}
static TranslationBlock *tb_find_physical(CPUState *cpu,
target_ulong pc,
target_ulong cs_base,
uint32_t flags)
{
CPUArchState *env = (CPUArchState *)cpu->env_ptr;
TranslationBlock *tb, **tb_hash_head, **ptb1;
unsigned int h;
tb_page_addr_t phys_pc, phys_page1;
tb_page_addr_t phys_pc;
struct tb_desc desc;
uint32_t h;
/* find translated block using physical mappings */
phys_pc = get_page_addr_code(env, pc);
phys_page1 = phys_pc & TARGET_PAGE_MASK;
h = tb_phys_hash_func(phys_pc);
/* Start at head of the hash entry */
ptb1 = tb_hash_head = &tcg_ctx.tb_ctx.tb_phys_hash[h];
tb = *ptb1;
while (tb) {
if (tb->pc == pc &&
tb->page_addr[0] == phys_page1 &&
tb->cs_base == cs_base &&
tb->flags == flags) {
if (tb->page_addr[1] == -1) {
/* done, we have a match */
break;
} else {
/* check next page if needed */
target_ulong virt_page2 = (pc & TARGET_PAGE_MASK) +
TARGET_PAGE_SIZE;
tb_page_addr_t phys_page2 = get_page_addr_code(env, virt_page2);
if (tb->page_addr[1] == phys_page2) {
break;
}
}
}
ptb1 = &tb->phys_hash_next;
tb = *ptb1;
}
if (tb) {
/* Move the TB to the head of the list */
*ptb1 = tb->phys_hash_next;
tb->phys_hash_next = *tb_hash_head;
*tb_hash_head = tb;
}
return tb;
desc.env = (CPUArchState *)cpu->env_ptr;
desc.cs_base = cs_base;
desc.flags = flags;
desc.pc = pc;
phys_pc = get_page_addr_code(desc.env, pc);
desc.phys_page1 = phys_pc & TARGET_PAGE_MASK;
h = tb_hash_func(phys_pc, pc, flags);
return qht_lookup(&tcg_ctx.tb_ctx.htable, tb_cmp, &desc, h);
}
static TranslationBlock *tb_find_slow(CPUState *cpu,

30
cpus.c
View File

@ -249,13 +249,13 @@ int64_t cpu_get_clock(void)
void cpu_enable_ticks(void)
{
/* Here, the really thing protected by seqlock is cpu_clock_offset. */
seqlock_write_lock(&timers_state.vm_clock_seqlock);
seqlock_write_begin(&timers_state.vm_clock_seqlock);
if (!timers_state.cpu_ticks_enabled) {
timers_state.cpu_ticks_offset -= cpu_get_host_ticks();
timers_state.cpu_clock_offset -= get_clock();
timers_state.cpu_ticks_enabled = 1;
}
seqlock_write_unlock(&timers_state.vm_clock_seqlock);
seqlock_write_end(&timers_state.vm_clock_seqlock);
}
/* disable cpu_get_ticks() : the clock is stopped. You must not call
@ -265,13 +265,13 @@ void cpu_enable_ticks(void)
void cpu_disable_ticks(void)
{
/* Here, the really thing protected by seqlock is cpu_clock_offset. */
seqlock_write_lock(&timers_state.vm_clock_seqlock);
seqlock_write_begin(&timers_state.vm_clock_seqlock);
if (timers_state.cpu_ticks_enabled) {
timers_state.cpu_ticks_offset += cpu_get_host_ticks();
timers_state.cpu_clock_offset = cpu_get_clock_locked();
timers_state.cpu_ticks_enabled = 0;
}
seqlock_write_unlock(&timers_state.vm_clock_seqlock);
seqlock_write_end(&timers_state.vm_clock_seqlock);
}
/* Correlation between real and virtual time is always going to be
@ -294,7 +294,7 @@ static void icount_adjust(void)
return;
}
seqlock_write_lock(&timers_state.vm_clock_seqlock);
seqlock_write_begin(&timers_state.vm_clock_seqlock);
cur_time = cpu_get_clock_locked();
cur_icount = cpu_get_icount_locked();
@ -315,7 +315,7 @@ static void icount_adjust(void)
last_delta = delta;
timers_state.qemu_icount_bias = cur_icount
- (timers_state.qemu_icount << icount_time_shift);
seqlock_write_unlock(&timers_state.vm_clock_seqlock);
seqlock_write_end(&timers_state.vm_clock_seqlock);
}
static void icount_adjust_rt(void *opaque)
@ -355,7 +355,7 @@ static void icount_warp_rt(void)
return;
}
seqlock_write_lock(&timers_state.vm_clock_seqlock);
seqlock_write_begin(&timers_state.vm_clock_seqlock);
if (runstate_is_running()) {
int64_t clock = REPLAY_CLOCK(REPLAY_CLOCK_VIRTUAL_RT,
cpu_get_clock_locked());
@ -374,7 +374,7 @@ static void icount_warp_rt(void)
timers_state.qemu_icount_bias += warp_delta;
}
vm_clock_warp_start = -1;
seqlock_write_unlock(&timers_state.vm_clock_seqlock);
seqlock_write_end(&timers_state.vm_clock_seqlock);
if (qemu_clock_expired(QEMU_CLOCK_VIRTUAL)) {
qemu_clock_notify(QEMU_CLOCK_VIRTUAL);
@ -399,9 +399,9 @@ void qtest_clock_warp(int64_t dest)
int64_t deadline = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL);
int64_t warp = qemu_soonest_timeout(dest - clock, deadline);
seqlock_write_lock(&timers_state.vm_clock_seqlock);
seqlock_write_begin(&timers_state.vm_clock_seqlock);
timers_state.qemu_icount_bias += warp;
seqlock_write_unlock(&timers_state.vm_clock_seqlock);
seqlock_write_end(&timers_state.vm_clock_seqlock);
qemu_clock_run_timers(QEMU_CLOCK_VIRTUAL);
timerlist_run_timers(aio_context->tlg.tl[QEMU_CLOCK_VIRTUAL]);
@ -468,9 +468,9 @@ void qemu_start_warp_timer(void)
* It is useful when we want a deterministic execution time,
* isolated from host latencies.
*/
seqlock_write_lock(&timers_state.vm_clock_seqlock);
seqlock_write_begin(&timers_state.vm_clock_seqlock);
timers_state.qemu_icount_bias += deadline;
seqlock_write_unlock(&timers_state.vm_clock_seqlock);
seqlock_write_end(&timers_state.vm_clock_seqlock);
qemu_clock_notify(QEMU_CLOCK_VIRTUAL);
} else {
/*
@ -481,11 +481,11 @@ void qemu_start_warp_timer(void)
* you will not be sending network packets continuously instead of
* every 100ms.
*/
seqlock_write_lock(&timers_state.vm_clock_seqlock);
seqlock_write_begin(&timers_state.vm_clock_seqlock);
if (vm_clock_warp_start == -1 || vm_clock_warp_start > clock) {
vm_clock_warp_start = clock;
}
seqlock_write_unlock(&timers_state.vm_clock_seqlock);
seqlock_write_end(&timers_state.vm_clock_seqlock);
timer_mod_anticipate(icount_warp_timer, clock + deadline);
}
} else if (deadline == 0) {
@ -621,7 +621,7 @@ int cpu_throttle_get_percentage(void)
void cpu_ticks_init(void)
{
seqlock_init(&timers_state.vm_clock_seqlock, NULL);
seqlock_init(&timers_state.vm_clock_seqlock);
vmstate_register(NULL, 0, &vmstate_timers, &timers_state);
throttle_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL_RT,
cpu_throttle_timer_tick, NULL);

2
include/exec/exec-all.h
View File

@ -215,8 +215,6 @@ struct TranslationBlock {
void *tc_ptr; /* pointer to the translated code */
uint8_t *tc_search; /* pointer to search data */
/* next matching tb for physical address. */
struct TranslationBlock *phys_hash_next;
/* original tb when cflags has CF_NOCACHE */
struct TranslationBlock *orig_tb;
/* first and second physical page containing code. The lower bit

7
include/exec/tb-context.h
View File

@ -21,9 +21,10 @@
#define QEMU_TB_CONTEXT_H_
#include "qemu/thread.h"
#include "qemu/qht.h"
#define CODE_GEN_PHYS_HASH_BITS 15
#define CODE_GEN_PHYS_HASH_SIZE (1 << CODE_GEN_PHYS_HASH_BITS)
#define CODE_GEN_HTABLE_BITS 15
#define CODE_GEN_HTABLE_SIZE (1 << CODE_GEN_HTABLE_BITS)
typedef struct TranslationBlock TranslationBlock;
typedef struct TBContext TBContext;
@ -31,7 +32,7 @@ typedef struct TBContext TBContext;
struct TBContext {
TranslationBlock *tbs;
TranslationBlock *tb_phys_hash[CODE_GEN_PHYS_HASH_SIZE];
struct qht htable;
int nb_tbs;
/* any access to the tbs or the page table must use this lock */
QemuMutex tb_lock;

94
include/exec/tb-hash-xx.h Normal file
View File

@ -0,0 +1,94 @@
/*
* xxHash - Fast Hash algorithm
* Copyright (C) 2012-2016, Yann Collet
*
* BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* + Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* + Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* You can contact the author at :
* - xxHash source repository : https://github.com/Cyan4973/xxHash
*/
#ifndef EXEC_TB_HASH_XX
#define EXEC_TB_HASH_XX
#include <qemu/bitops.h>
#define PRIME32_1 2654435761U
#define PRIME32_2 2246822519U
#define PRIME32_3 3266489917U
#define PRIME32_4 668265263U
#define PRIME32_5 374761393U
#define TB_HASH_XX_SEED 1
/*
* xxhash32, customized for input variables that are not guaranteed to be
* contiguous in memory.
*/
static inline
uint32_t tb_hash_func5(uint64_t a0, uint64_t b0, uint32_t e)
{
uint32_t v1 = TB_HASH_XX_SEED + PRIME32_1 + PRIME32_2;
uint32_t v2 = TB_HASH_XX_SEED + PRIME32_2;
uint32_t v3 = TB_HASH_XX_SEED + 0;
uint32_t v4 = TB_HASH_XX_SEED - PRIME32_1;
uint32_t a = a0 >> 32;
uint32_t b = a0;
uint32_t c = b0 >> 32;
uint32_t d = b0;
uint32_t h32;
v1 += a * PRIME32_2;
v1 = rol32(v1, 13);
v1 *= PRIME32_1;
v2 += b * PRIME32_2;
v2 = rol32(v2, 13);
v2 *= PRIME32_1;
v3 += c * PRIME32_2;
v3 = rol32(v3, 13);
v3 *= PRIME32_1;
v4 += d * PRIME32_2;
v4 = rol32(v4, 13);
v4 *= PRIME32_1;
h32 = rol32(v1, 1) + rol32(v2, 7) + rol32(v3, 12) + rol32(v4, 18);
h32 += 20;
h32 += e * PRIME32_3;
h32 = rol32(h32, 17) * PRIME32_4;
h32 ^= h32 >> 15;
h32 *= PRIME32_2;
h32 ^= h32 >> 13;
h32 *= PRIME32_3;
h32 ^= h32 >> 16;
return h32;
}
#endif /* EXEC_TB_HASH_XX */

7
include/exec/tb-hash.h
View File

@ -20,6 +20,8 @@
#ifndef EXEC_TB_HASH
#define EXEC_TB_HASH
#include "exec/tb-hash-xx.h"
/* Only the bottom TB_JMP_PAGE_BITS of the jump cache hash bits vary for
addresses on the same page. The top bits are the same. This allows
TLB invalidation to quickly clear a subset of the hash table. */
@ -43,9 +45,10 @@ static inline unsigned int tb_jmp_cache_hash_func(target_ulong pc)
| (tmp & TB_JMP_ADDR_MASK));
}
static inline unsigned int tb_phys_hash_func(tb_page_addr_t pc)
static inline
uint32_t tb_hash_func(tb_page_addr_t phys_pc, target_ulong pc, uint32_t flags)
{
return (pc >> 2) & (CODE_GEN_PHYS_HASH_SIZE - 1);
return tb_hash_func5(phys_pc, pc, flags);
}
#endif

2
include/qemu/compiler.h
View File

@ -41,6 +41,8 @@
# define QEMU_PACKED __attribute__((packed))
#endif
#define QEMU_ALIGNED(X) __attribute__((aligned(X)))
#ifndef glue
#define xglue(x, y) x ## y
#define glue(x, y) xglue(x, y)

30
include/qemu/processor.h Normal file
View File

@ -0,0 +1,30 @@
/*
* Copyright (C) 2016, Emilio G. Cota <cota@braap.org>
*
* License: GNU GPL, version 2.
* See the COPYING file in the top-level directory.
*/
#ifndef QEMU_PROCESSOR_H
#define QEMU_PROCESSOR_H
#include "qemu/atomic.h"
#if defined(__i386__) || defined(__x86_64__)
# define cpu_relax() asm volatile("rep; nop" ::: "memory")
#elif defined(__ia64__)
# define cpu_relax() asm volatile("hint @pause" ::: "memory")
#elif defined(__aarch64__)
# define cpu_relax() asm volatile("yield" ::: "memory")
#elif defined(__powerpc64__)
/* set Hardware Multi-Threading (HMT) priority to low; then back to medium */
# define cpu_relax() asm volatile("or 1, 1, 1;" \
"or 2, 2, 2;" ::: "memory")
#else
# define cpu_relax() barrier()
#endif
#endif /* QEMU_PROCESSOR_H */

63
include/qemu/qdist.h Normal file
View File

@ -0,0 +1,63 @@
/*
* Copyright (C) 2016, Emilio G. Cota <cota@braap.org>
*
* License: GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*/
#ifndef QEMU_QDIST_H
#define QEMU_QDIST_H
#include "qemu/osdep.h"
#include "qemu-common.h"
#include "qemu/bitops.h"
/*
* Samples with the same 'x value' end up in the same qdist_entry,
* e.g. inc(0.1) and inc(0.1) end up as {x=0.1, count=2}.
*
* Binning happens only at print time, so that we retain the flexibility to
* choose the binning. This might not be ideal for workloads that do not care
* much about precision and insert many samples all with different x values;
* in that case, pre-binning (e.g. entering both 0.115 and 0.097 as 0.1)
* should be considered.
*/
struct qdist_entry {
double x;
unsigned long count;
};
struct qdist {
struct qdist_entry *entries;
size_t n;
size_t size;
};
#define QDIST_PR_BORDER BIT(0)
#define QDIST_PR_LABELS BIT(1)
/* the remaining options only work if PR_LABELS is set */
#define QDIST_PR_NODECIMAL BIT(2)
#define QDIST_PR_PERCENT BIT(3)
#define QDIST_PR_100X BIT(4)
#define QDIST_PR_NOBINRANGE BIT(5)
void qdist_init(struct qdist *dist);
void qdist_destroy(struct qdist *dist);
void qdist_add(struct qdist *dist, double x, long count);
void qdist_inc(struct qdist *dist, double x);
double qdist_xmin(const struct qdist *dist);
double qdist_xmax(const struct qdist *dist);
double qdist_avg(const struct qdist *dist);
unsigned long qdist_sample_count(const struct qdist *dist);
size_t qdist_unique_entries(const struct qdist *dist);
/* callers must free the returned string with g_free() */
char *qdist_pr_plain(const struct qdist *dist, size_t n_groups);
/* callers must free the returned string with g_free() */
char *qdist_pr(const struct qdist *dist, size_t n_groups, uint32_t opt);
/* Only qdist code and test code should ever call this function */
void qdist_bin__internal(struct qdist *to, const struct qdist *from, size_t n);
#endif /* QEMU_QDIST_H */

183
include/qemu/qht.h Normal file
View File

@ -0,0 +1,183 @@
/*
* Copyright (C) 2016, Emilio G. Cota <cota@braap.org>
*
* License: GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*/
#ifndef QEMU_QHT_H
#define QEMU_QHT_H
#include "qemu/osdep.h"
#include "qemu/seqlock.h"
#include "qemu/thread.h"
#include "qemu/qdist.h"
struct qht {
struct qht_map *map;
QemuMutex lock; /* serializes setters of ht->map */
unsigned int mode;
};
/**
* struct qht_stats - Statistics of a QHT
* @head_buckets: number of head buckets
* @used_head_buckets: number of non-empty head buckets
* @entries: total number of entries
* @chain: frequency distribution representing the number of buckets in each
* chain, excluding empty chains.
* @occupancy: frequency distribution representing chain occupancy rate.
* Valid range: from 0.0 (empty) to 1.0 (full occupancy).
*
* An entry is a pointer-hash pair.
* Each bucket can host several entries.
* Chains are chains of buckets, whose first link is always a head bucket.
*/
struct qht_stats {
size_t head_buckets;
size_t used_head_buckets;
size_t entries;
struct qdist chain;
struct qdist occupancy;
};
typedef bool (*qht_lookup_func_t)(const void *obj, const void *userp);
typedef void (*qht_iter_func_t)(struct qht *ht, void *p, uint32_t h, void *up);
#define QHT_MODE_AUTO_RESIZE 0x1 /* auto-resize when heavily loaded */
/**
* qht_init - Initialize a QHT
* @ht: QHT to be initialized
* @n_elems: number of entries the hash table should be optimized for.
* @mode: bitmask with OR'ed QHT_MODE_*
*/
void qht_init(struct qht *ht, size_t n_elems, unsigned int mode);
/**
* qht_destroy - destroy a previously initialized QHT
* @ht: QHT to be destroyed
*
* Call only when there are no readers/writers left.
*/
void qht_destroy(struct qht *ht);
/**
* qht_insert - Insert a pointer into the hash table
* @ht: QHT to insert to
* @p: pointer to be inserted
* @hash: hash corresponding to @p
*
* Attempting to insert a NULL @p is a bug.
* Inserting the same pointer @p with different @hash values is a bug.
*
* Returns true on sucess.
* Returns false if the @p-@hash pair already exists in the hash table.
*/
bool qht_insert(struct qht *ht, void *p, uint32_t hash);
/**
* qht_lookup - Look up a pointer in a QHT
* @ht: QHT to be looked up
* @func: function to compare existing pointers against @userp
* @userp: pointer to pass to @func
* @hash: hash of the pointer to be looked up
*
* Needs to be called under an RCU read-critical section.
*
* The user-provided @func compares pointers in QHT against @userp.
* If the function returns true, a match has been found.
*
* Returns the corresponding pointer when a match is found.
* Returns NULL otherwise.
*/
void *qht_lookup(struct qht *ht, qht_lookup_func_t func, const void *userp,
uint32_t hash);
/**
* qht_remove - remove a pointer from the hash table
* @ht: QHT to remove from
* @p: pointer to be removed
* @hash: hash corresponding to @p
*
* Attempting to remove a NULL @p is a bug.
*
* Just-removed @p pointers cannot be immediately freed; they need to remain
* valid until the end of the RCU grace period in which qht_remove() is called.
* This guarantees that concurrent lookups will always compare against valid
* data.
*
* Returns true on success.
* Returns false if the @p-@hash pair was not found.
*/
bool qht_remove(struct qht *ht, const void *p, uint32_t hash);
/**
* qht_reset - reset a QHT
* @ht: QHT to be reset
*
* All entries in the hash table are reset. No resizing is performed.
*
* If concurrent readers may exist, the objects pointed to by the hash table
* must remain valid for the existing RCU grace period -- see qht_remove().
* See also: qht_reset_size()
*/
void qht_reset(struct qht *ht);
/**
* qht_reset_size - reset and resize a QHT
* @ht: QHT to be reset and resized
* @n_elems: number of entries the resized hash table should be optimized for.
*
* Returns true if the resize was necessary and therefore performed.
* Returns false otherwise.
*
* If concurrent readers may exist, the objects pointed to by the hash table
* must remain valid for the existing RCU grace period -- see qht_remove().
* See also: qht_reset(), qht_resize().
*/
bool qht_reset_size(struct qht *ht, size_t n_elems);
/**
* qht_resize - resize a QHT
* @ht: QHT to be resized
* @n_elems: number of entries the resized hash table should be optimized for
*
* Returns true on success.
* Returns false if the resize was not necessary and therefore not performed.
* See also: qht_reset_size().
*/
bool qht_resize(struct qht *ht, size_t n_elems);
/**
* qht_iter - Iterate over a QHT
* @ht: QHT to be iterated over
* @func: function to be called for each entry in QHT
* @userp: additional pointer to be passed to @func
*
* Each time it is called, user-provided @func is passed a pointer-hash pair,
* plus @userp.
*/
void qht_iter(struct qht *ht, qht_iter_func_t func, void *userp);
/**
* qht_statistics_init - Gather statistics from a QHT
* @ht: QHT to gather statistics from
* @stats: pointer to a struct qht_stats to be filled in
*
* Does NOT need to be called under an RCU read-critical section,
* since it does not dereference any pointers stored in the hash table.
*
* When done with @stats, pass the struct to qht_statistics_destroy().
* Failing to do this will leak memory.
*/
void qht_statistics_init(struct qht *ht, struct qht_stats *stats);
/**
* qht_statistics_destroy - Destroy a struct qht_stats
* @stats: stuct qht_stats to be destroyed
*
* See also: qht_statistics_init().
*/
void qht_statistics_destroy(struct qht_stats *stats);
#endif /* QEMU_QHT_H */

14
include/qemu/seqlock.h
View File

@ -19,37 +19,29 @@
typedef struct QemuSeqLock QemuSeqLock;
struct QemuSeqLock {
QemuMutex *mutex;
unsigned sequence;
};
static inline void seqlock_init(QemuSeqLock *sl, QemuMutex *mutex)
static inline void seqlock_init(QemuSeqLock *sl)
{
sl->mutex = mutex;
sl->sequence = 0;
}
/* Lock out other writers and update the count. */
static inline void seqlock_write_lock(QemuSeqLock *sl)
static inline void seqlock_write_begin(QemuSeqLock *sl)
{
if (sl->mutex) {
qemu_mutex_lock(sl->mutex);
}
++sl->sequence;
/* Write sequence before updating other fields. */
smp_wmb();
}
static inline void seqlock_write_unlock(QemuSeqLock *sl)
static inline void seqlock_write_end(QemuSeqLock *sl)
{
/* Write other fields before finalizing sequence. */
smp_wmb();
++sl->sequence;
if (sl->mutex) {
qemu_mutex_unlock(sl->mutex);
}
}
static inline unsigned seqlock_read_begin(QemuSeqLock *sl)

35
include/qemu/thread.h
View File

@ -1,6 +1,8 @@
#ifndef __QEMU_THREAD_H
#define __QEMU_THREAD_H 1
#include "qemu/processor.h"
#include "qemu/atomic.h"
typedef struct QemuMutex QemuMutex;
typedef struct QemuCond QemuCond;
@ -60,4 +62,37 @@ struct Notifier;
void qemu_thread_atexit_add(struct Notifier *notifier);
void qemu_thread_atexit_remove(struct Notifier *notifier);
typedef struct QemuSpin {
int value;
} QemuSpin;
static inline void qemu_spin_init(QemuSpin *spin)
{
__sync_lock_release(&spin->value);
}
static inline void qemu_spin_lock(QemuSpin *spin)
{
while (unlikely(__sync_lock_test_and_set(&spin->value, true))) {
while (atomic_read(&spin->value)) {
cpu_relax();
}
}
}
static inline bool qemu_spin_trylock(QemuSpin *spin)
{
return __sync_lock_test_and_set(&spin->value, true);
}
static inline bool qemu_spin_locked(QemuSpin *spin)
{
return atomic_read(&spin->value);
}
static inline void qemu_spin_unlock(QemuSpin *spin)
{
__sync_lock_release(&spin->value);
}
#endif

4
tests/.gitignore vendored
View File

@ -7,6 +7,7 @@ check-qnull
check-qstring
check-qom-interface
check-qom-proplist
qht-bench
rcutorture
test-aio
test-base64
@ -48,7 +49,10 @@ test-qapi-types.[ch]
test-qapi-visit.[ch]
test-qdev-global-props
test-qemu-opts
test-qdist
test-qga
test-qht
test-qht-par
test-qmp-commands
test-qmp-commands.h
test-qmp-event

14
tests/Makefile.include
View File

@ -70,6 +70,12 @@ check-unit-y += tests/rcutorture$(EXESUF)
gcov-files-rcutorture-y = util/rcu.c
check-unit-y += tests/test-rcu-list$(EXESUF)
gcov-files-test-rcu-list-y = util/rcu.c
check-unit-y += tests/test-qdist$(EXESUF)
gcov-files-test-qdist-y = util/qdist.c
check-unit-y += tests/test-qht$(EXESUF)
gcov-files-test-qht-y = util/qht.c
check-unit-y += tests/test-qht-par$(EXESUF)
gcov-files-test-qht-par-y = util/qht.c
check-unit-y += tests/test-bitops$(EXESUF)
check-unit-$(CONFIG_HAS_GLIB_SUBPROCESS_TESTS) += tests/test-qdev-global-props$(EXESUF)
check-unit-y += tests/check-qom-interface$(EXESUF)
@ -394,7 +400,9 @@ test-obj-y = tests/check-qint.o tests/check-qstring.o tests/check-qdict.o \
tests/test-qmp-commands.o tests/test-visitor-serialization.o \
tests/test-x86-cpuid.o tests/test-mul64.o tests/test-int128.o \
tests/test-opts-visitor.o tests/test-qmp-event.o \
tests/rcutorture.o tests/test-rcu-list.o
tests/rcutorture.o tests/test-rcu-list.o \
tests/test-qdist.o \
tests/test-qht.o tests/qht-bench.o tests/test-qht-par.o
$(test-obj-y): QEMU_INCLUDES += -Itests
QEMU_CFLAGS += -I$(SRC_PATH)/tests
@ -433,6 +441,10 @@ tests/test-cutils$(EXESUF): tests/test-cutils.o util/cutils.o
tests/test-int128$(EXESUF): tests/test-int128.o
tests/rcutorture$(EXESUF): tests/rcutorture.o $(test-util-obj-y)
tests/test-rcu-list$(EXESUF): tests/test-rcu-list.o $(test-util-obj-y)
tests/test-qdist$(EXESUF): tests/test-qdist.o $(test-util-obj-y)
tests/test-qht$(EXESUF): tests/test-qht.o $(test-util-obj-y)
tests/test-qht-par$(EXESUF): tests/test-qht-par.o tests/qht-bench$(EXESUF) $(test-util-obj-y)
tests/qht-bench$(EXESUF): tests/qht-bench.o $(test-util-obj-y)
tests/test-qdev-global-props$(EXESUF): tests/test-qdev-global-props.o \
hw/core/qdev.o hw/core/qdev-properties.o hw/core/hotplug.o\

488
tests/qht-bench.c Normal file
View File

@ -0,0 +1,488 @@
/*
* Copyright (C) 2016, Emilio G. Cota <cota@braap.org>
*
* License: GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*/
#include "qemu/osdep.h"
#include <glib.h>
#include "qemu/processor.h"
#include "qemu/atomic.h"
#include "qemu/qht.h"
#include "qemu/rcu.h"
#include "exec/tb-hash-xx.h"
struct thread_stats {
size_t rd;
size_t not_rd;
size_t in;
size_t not_in;
size_t rm;
size_t not_rm;
size_t rz;
size_t not_rz;
};
struct thread_info {
void (*func)(struct thread_info *);
struct thread_stats stats;
uint64_t r;
bool write_op; /* writes alternate between insertions and removals */
bool resize_down;
} QEMU_ALIGNED(64); /* avoid false sharing among threads */
static struct qht ht;
static QemuThread *rw_threads;
#define DEFAULT_RANGE (4096)
#define DEFAULT_QHT_N_ELEMS DEFAULT_RANGE
static unsigned int duration = 1;
static unsigned int n_rw_threads = 1;
static unsigned long lookup_range = DEFAULT_RANGE;
static unsigned long update_range = DEFAULT_RANGE;
static size_t init_range = DEFAULT_RANGE;
static size_t init_size = DEFAULT_RANGE;
static size_t n_ready_threads;
static long populate_offset;
static long *keys;
static size_t resize_min;
static size_t resize_max;
static struct thread_info *rz_info;
static unsigned long resize_delay = 1000;
static double resize_rate; /* 0.0 to 1.0 */
static unsigned int n_rz_threads = 1;
static QemuThread *rz_threads;
static double update_rate; /* 0.0 to 1.0 */
static uint64_t update_threshold;
static uint64_t resize_threshold;
static size_t qht_n_elems = DEFAULT_QHT_N_ELEMS;
static int qht_mode;
static bool test_start;
static bool test_stop;
static struct thread_info *rw_info;
static const char commands_string[] =
" -d = duration, in seconds\n"
" -n = number of threads\n"
"\n"
" -o = offset at which keys start\n"
"\n"
" -g = set -s,-k,-K,-l,-r to the same value\n"
" -s = initial size hint\n"
" -k = initial number of keys\n"
" -K = initial range of keys (will be rounded up to pow2)\n"
" -l = lookup range of keys (will be rounded up to pow2)\n"
" -r = update range of keys (will be rounded up to pow2)\n"
"\n"
" -u = update rate (0.0 to 100.0), 50/50 split of insertions/removals\n"
"\n"
" -R = enable auto-resize\n"
" -S = resize rate (0.0 to 100.0)\n"
" -D = delay (in us) between potential resizes\n"
" -N = number of resize threads";
static void usage_complete(int argc, char *argv[])
{
fprintf(stderr, "Usage: %s [options]\n", argv[0]);
fprintf(stderr, "options:\n%s\n", commands_string);
exit(-1);
}
static bool is_equal(const void *obj, const void *userp)
{
const long *a = obj;
const long *b = userp;
return *a == *b;
}
static inline uint32_t h(unsigned long v)
{
return tb_hash_func5(v, 0, 0);
}
/*
* From: https://en.wikipedia.org/wiki/Xorshift
* This is faster than rand_r(), and gives us a wider range (RAND_MAX is only
* guaranteed to be >= INT_MAX).
*/
static uint64_t xorshift64star(uint64_t x)
{
x ^= x >> 12; /* a */
x ^= x << 25; /* b */
x ^= x >> 27; /* c */
return x * UINT64_C(2685821657736338717);
}
static void do_rz(struct thread_info *info)
{
struct thread_stats *stats = &info->stats;
if (info->r < resize_threshold) {
size_t size = info->resize_down ? resize_min : resize_max;
bool resized;
resized = qht_resize(&ht, size);
info->resize_down = !info->resize_down;
if (resized) {
stats->rz++;
} else {
stats->not_rz++;
}
}
g_usleep(resize_delay);
}
static void do_rw(struct thread_info *info)
{
struct thread_stats *stats = &info->stats;
uint32_t hash;
long *p;
if (info->r >= update_threshold) {
bool read;
p = &keys[info->r & (lookup_range - 1)];
hash = h(*p);
read = qht_lookup(&ht, is_equal, p, hash);
if (read) {
stats->rd++;
} else {
stats->not_rd++;
}
} else {
p = &keys[info->r & (update_range - 1)];
hash = h(*p);
if (info->write_op) {
bool written = false;
if (qht_lookup(&ht, is_equal, p, hash) == NULL) {
written = qht_insert(&ht, p, hash);
}
if (written) {
stats->in++;
} else {
stats->not_in++;
}
} else {
bool removed = false;
if (qht_lookup(&ht, is_equal, p, hash)) {
removed = qht_remove(&ht, p, hash);
}
if (removed) {
stats->rm++;
} else {
stats->not_rm++;
}
}
info->write_op = !info->write_op;
}
}
static void *thread_func(void *p)
{
struct thread_info *info = p;
rcu_register_thread();
atomic_inc(&n_ready_threads);
while (!atomic_mb_read(&test_start)) {
cpu_relax();
}
rcu_read_lock();
while (!atomic_read(&test_stop)) {
info->r = xorshift64star(info->r);
info->func(info);
}
rcu_read_unlock();
rcu_unregister_thread();
return NULL;
}
/* sets everything except info->func */
static void prepare_thread_info(struct thread_info *info, int i)
{
/* seed for the RNG; each thread should have a different one */
info->r = (i + 1) ^ time(NULL);
/* the first update will be a write */
info->write_op = true;
/* the first resize will be down */
info->resize_down = true;
memset(&info->stats, 0, sizeof(info->stats));
}
static void
th_create_n(QemuThread **threads, struct thread_info **infos, const char *name,
void (*func)(struct thread_info *), int offset, int n)
{
struct thread_info *info;
QemuThread *th;
int i;
th = g_malloc(sizeof(*th) * n);
*threads = th;
info = qemu_memalign(64, sizeof(*info) * n);
*infos = info;
for (i = 0; i < n; i++) {
prepare_thread_info(&info[i], offset + i);
info[i].func = func;
qemu_thread_create(&th[i], name, thread_func, &info[i],
QEMU_THREAD_JOINABLE);
}
}
static void create_threads(void)
{
th_create_n(&rw_threads, &rw_info, "rw", do_rw, 0, n_rw_threads);
th_create_n(&rz_threads, &rz_info, "rz", do_rz, n_rw_threads, n_rz_threads);
}
static void pr_params(void)
{
printf("Parameters:\n");
printf(" duration: %d s\n", duration);
printf(" # of threads: %u\n", n_rw_threads);
printf(" initial # of keys: %zu\n", init_size);
printf(" initial size hint: %zu\n", qht_n_elems);
printf(" auto-resize: %s\n",
qht_mode & QHT_MODE_AUTO_RESIZE ? "on" : "off");
if (resize_rate) {
printf(" resize_rate: %f%%\n", resize_rate * 100.0);
printf(" resize range: %zu-%zu\n", resize_min, resize_max);
printf(" # resize threads %u\n", n_rz_threads);
}
printf(" update rate: %f%%\n", update_rate * 100.0);
printf(" offset: %ld\n", populate_offset);
printf(" initial key range: %zu\n", init_range);
printf(" lookup range: %lu\n", lookup_range);
printf(" update range: %lu\n", update_range);
}
static void do_threshold(double rate, uint64_t *threshold)
{
if (rate == 1.0) {
*threshold = UINT64_MAX;
} else {
*threshold = rate * UINT64_MAX;
}
}
static void htable_init(void)
{
unsigned long n = MAX(init_range, update_range);
uint64_t r = time(NULL);
size_t retries = 0;
size_t i;
/* avoid allocating memory later by allocating all the keys now */
keys = g_malloc(sizeof(*keys) * n);
for (i = 0; i < n; i++) {
keys[i] = populate_offset + i;
}
/* some sanity checks */
g_assert_cmpuint(lookup_range, <=, n);
/* compute thresholds */
do_threshold(update_rate, &update_threshold);
do_threshold(resize_rate, &resize_threshold);
if (resize_rate) {
resize_min = n / 2;
resize_max = n;
assert(resize_min < resize_max);
} else {
n_rz_threads = 0;
}
/* initialize the hash table */
qht_init(&ht, qht_n_elems, qht_mode);
assert(init_size <= init_range);
pr_params();
fprintf(stderr, "Initialization: populating %zu items...", init_size);
for (i = 0; i < init_size; i++) {
for (;;) {
uint32_t hash;
long *p;
r = xorshift64star(r);
p = &keys[r & (init_range - 1)];
hash = h(*p);
if (qht_insert(&ht, p, hash)) {
break;
}
retries++;
}
}
fprintf(stderr, " populated after %zu retries\n", retries);
}
static void add_stats(struct thread_stats *s, struct thread_info *info, int n)
{
int i;
for (i = 0; i < n; i++) {
struct thread_stats *stats = &info[i].stats;
s->rd += stats->rd;
s->not_rd += stats->not_rd;
s->in += stats->in;
s->not_in += stats->not_in;
s->rm += stats->rm;
s->not_rm += stats->not_rm;
s->rz += stats->rz;
s->not_rz += stats->not_rz;
}
}
static void pr_stats(void)
{
struct thread_stats s = {};
double tx;
add_stats(&s, rw_info, n_rw_threads);
add_stats(&s, rz_info, n_rz_threads);
printf("Results:\n");
if (resize_rate) {
printf(" Resizes: %zu (%.2f%% of %zu)\n",
s.rz, (double)s.rz / (s.rz + s.not_rz) * 100, s.rz + s.not_rz);
}
printf(" Read: %.2f M (%.2f%% of %.2fM)\n",
(double)s.rd / 1e6,
(double)s.rd / (s.rd + s.not_rd) * 100,
(double)(s.rd + s.not_rd) / 1e6);
printf(" Inserted: %.2f M (%.2f%% of %.2fM)\n",
(double)s.in / 1e6,
(double)s.in / (s.in + s.not_in) * 100,
(double)(s.in + s.not_in) / 1e6);
printf(" Removed: %.2f M (%.2f%% of %.2fM)\n",
(double)s.rm / 1e6,
(double)s.rm / (s.rm + s.not_rm) * 100,
(double)(s.rm + s.not_rm) / 1e6);
tx = (s.rd + s.not_rd + s.in + s.not_in + s.rm + s.not_rm) / 1e6 / duration;
printf(" Throughput: %.2f MT/s\n", tx);
printf(" Throughput/thread: %.2f MT/s/thread\n", tx / n_rw_threads);
}
static void run_test(void)
{
unsigned int remaining;
int i;
while (atomic_read(&n_ready_threads) != n_rw_threads + n_rz_threads) {
cpu_relax();
}
atomic_mb_set(&test_start, true);
do {
remaining = sleep(duration);
} while (remaining);
atomic_mb_set(&test_stop, true);
for (i = 0; i < n_rw_threads; i++) {
qemu_thread_join(&rw_threads[i]);
}
for (i = 0; i < n_rz_threads; i++) {
qemu_thread_join(&rz_threads[i]);
}
}
static void parse_args(int argc, char *argv[])
{
int c;
for (;;) {
c = getopt(argc, argv, "d:D:g:k:K:l:hn:N:o:r:Rs:S:u:");
if (c < 0) {
break;
}
switch (c) {
case 'd':
duration = atoi(optarg);
break;
case 'D':
resize_delay = atol(optarg);
break;
case 'g':
init_range = pow2ceil(atol(optarg));
lookup_range = pow2ceil(atol(optarg));
update_range = pow2ceil(atol(optarg));
qht_n_elems = atol(optarg);
init_size = atol(optarg);
break;
case 'h':
usage_complete(argc, argv);
exit(0);
case 'k':
init_size = atol(optarg);
break;
case 'K':
init_range = pow2ceil(atol(optarg));
break;
case 'l':
lookup_range = pow2ceil(atol(optarg));
break;
case 'n':
n_rw_threads = atoi(optarg);
break;
case 'N':
n_rz_threads = atoi(optarg);
break;
case 'o':
populate_offset = atol(optarg);
break;
case 'r':
update_range = pow2ceil(atol(optarg));
break;
case 'R':
qht_mode |= QHT_MODE_AUTO_RESIZE;
break;
case 's':
qht_n_elems = atol(optarg);
break;
case 'S':
resize_rate = atof(optarg) / 100.0;
if (resize_rate > 1.0) {
resize_rate = 1.0;
}
break;
case 'u':
update_rate = atof(optarg) / 100.0;
if (update_rate > 1.0) {
update_rate = 1.0;
}
break;
}
}
}
int main(int argc, char *argv[])
{
parse_args(argc, argv);
htable_init();
create_threads();
run_test();
pr_stats();
return 0;
}

384
tests/test-qdist.c Normal file
View File

@ -0,0 +1,384 @@
/*
* Copyright (C) 2016, Emilio G. Cota <cota@braap.org>
*
* License: GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*/
#include "qemu/osdep.h"
#include <glib.h>
#include "qemu/qdist.h"
#include <math.h>
struct entry_desc {
double x;
unsigned long count;
/* 0 prints a space, 1-8 prints from qdist_blocks[] */
int fill_code;
};
/* See: https://en.wikipedia.org/wiki/Block_Elements */
static const gunichar qdist_blocks[] = {
0x2581,
0x2582,
0x2583,
0x2584,
0x2585,
0x2586,
0x2587,
0x2588
};
#define QDIST_NR_BLOCK_CODES ARRAY_SIZE(qdist_blocks)
static char *pr_hist(const struct entry_desc *darr, size_t n)
{
GString *s = g_string_new("");
size_t i;
for (i = 0; i < n; i++) {
int fill = darr[i].fill_code;
if (fill) {
assert(fill <= QDIST_NR_BLOCK_CODES);
g_string_append_unichar(s, qdist_blocks[fill - 1]);
} else {
g_string_append_c(s, ' ');
}
}
return g_string_free(s, FALSE);
}
static void
histogram_check(const struct qdist *dist, const struct entry_desc *darr,
size_t n, size_t n_bins)
{
char *pr = qdist_pr_plain(dist, n_bins);
char *str = pr_hist(darr, n);
g_assert_cmpstr(pr, ==, str);
g_free(pr);
g_free(str);
}
static void histogram_check_single_full(const struct qdist *dist, size_t n_bins)
{
struct entry_desc desc = { .fill_code = 8 };
histogram_check(dist, &desc, 1, n_bins);
}
static void
entries_check(const struct qdist *dist, const struct entry_desc *darr, size_t n)
{
size_t i;
for (i = 0; i < n; i++) {
struct qdist_entry *e = &dist->entries[i];
g_assert_cmpuint(e->count, ==, darr[i].count);
}
}
static void
entries_insert(struct qdist *dist, const struct entry_desc *darr, size_t n)
{
size_t i;
for (i = 0; i < n; i++) {
qdist_add(dist, darr[i].x, darr[i].count);
}
}
static void do_test_bin(const struct entry_desc *a, size_t n_a,
const struct entry_desc *b, size_t n_b)
{
struct qdist qda;
struct qdist qdb;
qdist_init(&qda);
entries_insert(&qda, a, n_a);
qdist_inc(&qda, a[0].x);
qdist_add(&qda, a[0].x, -1);
g_assert_cmpuint(qdist_unique_entries(&qda), ==, n_a);
g_assert_cmpfloat(qdist_xmin(&qda), ==, a[0].x);
g_assert_cmpfloat(qdist_xmax(&qda), ==, a[n_a - 1].x);
histogram_check(&qda, a, n_a, 0);
histogram_check(&qda, a, n_a, n_a);
qdist_bin__internal(&qdb, &qda, n_b);
g_assert_cmpuint(qdb.n, ==, n_b);
entries_check(&qdb, b, n_b);
g_assert_cmpuint(qdist_sample_count(&qda), ==, qdist_sample_count(&qdb));
/*
* No histogram_check() for $qdb, since we'd rebin it and that is a bug.
* Instead, regenerate it from $qda.
*/
histogram_check(&qda, b, n_b, n_b);
qdist_destroy(&qdb);
qdist_destroy(&qda);
}
static void do_test_pr(uint32_t opt)
{
static const struct entry_desc desc[] = {
[0] = { 1, 900, 8 },
[1] = { 2, 1, 1 },
[2] = { 3, 2, 1 }
};
static const char border[] = "|";
const char *llabel = NULL;
const char *rlabel = NULL;
struct qdist dist;
GString *s;
char *str;
char *pr;
size_t n;
n = ARRAY_SIZE(desc);
qdist_init(&dist);
entries_insert(&dist, desc, n);
histogram_check(&dist, desc, n, 0);
s = g_string_new("");
if (opt & QDIST_PR_LABELS) {
unsigned int lopts = opt & (QDIST_PR_NODECIMAL |
QDIST_PR_PERCENT |
QDIST_PR_100X |
QDIST_PR_NOBINRANGE);
if (lopts == 0) {
llabel = "[1.0,1.7)";
rlabel = "[2.3,3.0]";
} else if (lopts == QDIST_PR_NODECIMAL) {
llabel = "[1,2)";
rlabel = "[2,3]";
} else if (lopts == (QDIST_PR_PERCENT | QDIST_PR_NODECIMAL)) {
llabel = "[1,2)%";
rlabel = "[2,3]%";
} else if (lopts == QDIST_PR_100X) {
llabel = "[100.0,166.7)";
rlabel = "[233.3,300.0]";
} else if (lopts == (QDIST_PR_NOBINRANGE | QDIST_PR_NODECIMAL)) {
llabel = "1";
rlabel = "3";
} else {
g_assert_cmpstr("BUG", ==, "This is not meant to be exhaustive");
}
}
if (llabel) {
g_string_append(s, llabel);
}
if (opt & QDIST_PR_BORDER) {
g_string_append(s, border);
}
str = pr_hist(desc, n);
g_string_append(s, str);
g_free(str);
if (opt & QDIST_PR_BORDER) {
g_string_append(s, border);
}
if (rlabel) {
g_string_append(s, rlabel);
}
str = g_string_free(s, FALSE);
pr = qdist_pr(&dist, n, opt);
g_assert_cmpstr(pr, ==, str);
g_free(pr);
g_free(str);
qdist_destroy(&dist);
}
static inline void do_test_pr_label(uint32_t opt)
{
opt |= QDIST_PR_LABELS;
do_test_pr(opt);
}
static void test_pr(void)
{
do_test_pr(0);
do_test_pr(QDIST_PR_BORDER);
/* 100X should be ignored because we're not setting LABELS */
do_test_pr(QDIST_PR_100X);
do_test_pr_label(0);
do_test_pr_label(QDIST_PR_NODECIMAL);
do_test_pr_label(QDIST_PR_PERCENT | QDIST_PR_NODECIMAL);
do_test_pr_label(QDIST_PR_100X);
do_test_pr_label(QDIST_PR_NOBINRANGE | QDIST_PR_NODECIMAL);
}
static void test_bin_shrink(void)
{
static const struct entry_desc a[] = {
[0] = { 0.0, 42922, 7 },
[1] = { 0.25, 47834, 8 },
[2] = { 0.50, 26628, 0 },
[3] = { 0.625, 597, 4 },
[4] = { 0.75, 10298, 1 },
[5] = { 0.875, 22, 2 },
[6] = { 1.0, 2771, 1 }
};
static const struct entry_desc b[] = {
[0] = { 0.0, 42922, 7 },
[1] = { 0.25, 47834, 8 },
[2] = { 0.50, 27225, 3 },
[3] = { 0.75, 13091, 1 }
};
return do_test_bin(a, ARRAY_SIZE(a), b, ARRAY_SIZE(b));
}
static void test_bin_expand(void)
{
static const struct entry_desc a[] = {
[0] = { 0.0, 11713, 5 },
[1] = { 0.25, 20294, 0 },
[2] = { 0.50, 17266, 8 },
[3] = { 0.625, 1506, 0 },
[4] = { 0.75, 10355, 6 },
[5] = { 0.833, 2, 1 },
[6] = { 0.875, 99, 4 },
[7] = { 1.0, 4301, 2 }
};
static const struct entry_desc b[] = {
[0] = { 0.0, 11713, 5 },
[1] = { 0.0, 0, 0 },
[2] = { 0.0, 20294, 8 },
[3] = { 0.0, 0, 0 },
[4] = { 0.0, 0, 0 },
[5] = { 0.0, 17266, 6 },
[6] = { 0.0, 1506, 1 },
[7] = { 0.0, 10355, 4 },
[8] = { 0.0, 101, 1 },
[9] = { 0.0, 4301, 2 }
};
return do_test_bin(a, ARRAY_SIZE(a), b, ARRAY_SIZE(b));
}
static void test_bin_precision(void)
{
static const struct entry_desc a[] = {
[0] = { 0, 213549, 8 },
[1] = { 1, 70, 1 },
};
static const struct entry_desc b[] = {
[0] = { 0, 213549, 8 },
[1] = { 0, 70, 1 },
};
return do_test_bin(a, ARRAY_SIZE(a), b, ARRAY_SIZE(b));
}
static void test_bin_simple(void)
{
static const struct entry_desc a[] = {
[0] = { 10, 101, 8 },
[1] = { 11, 0, 0 },
[2] = { 12, 2, 1 }
};
static const struct entry_desc b[] = {
[0] = { 0, 101, 8 },
[1] = { 0, 0, 0 },
[2] = { 0, 0, 0 },
[3] = { 0, 0, 0 },
[4] = { 0, 2, 1 }
};
return do_test_bin(a, ARRAY_SIZE(a), b, ARRAY_SIZE(b));
}
static void test_single_full(void)
{
struct qdist dist;
qdist_init(&dist);
qdist_add(&dist, 3, 102);
g_assert_cmpfloat(qdist_avg(&dist), ==, 3);
g_assert_cmpfloat(qdist_xmin(&dist), ==, 3);
g_assert_cmpfloat(qdist_xmax(&dist), ==, 3);
histogram_check_single_full(&dist, 0);
histogram_check_single_full(&dist, 1);
histogram_check_single_full(&dist, 10);
qdist_destroy(&dist);
}
static void test_single_empty(void)
{
struct qdist dist;
char *pr;
qdist_init(&dist);
qdist_add(&dist, 3, 0);
g_assert_cmpuint(qdist_sample_count(&dist), ==, 0);
g_assert(isnan(qdist_avg(&dist)));
g_assert_cmpfloat(qdist_xmin(&dist), ==, 3);
g_assert_cmpfloat(qdist_xmax(&dist), ==, 3);
pr = qdist_pr_plain(&dist, 0);
g_assert_cmpstr(pr, ==, " ");
g_free(pr);
pr = qdist_pr_plain(&dist, 1);
g_assert_cmpstr(pr, ==, " ");
g_free(pr);
pr = qdist_pr_plain(&dist, 2);
g_assert_cmpstr(pr, ==, " ");
g_free(pr);
qdist_destroy(&dist);
}
static void test_none(void)
{
struct qdist dist;
char *pr;
qdist_init(&dist);
g_assert(isnan(qdist_avg(&dist)));
g_assert(isnan(qdist_xmin(&dist)));
g_assert(isnan(qdist_xmax(&dist)));
pr = qdist_pr_plain(&dist, 0);
g_assert(pr == NULL);
pr = qdist_pr_plain(&dist, 2);
g_assert(pr == NULL);
qdist_destroy(&dist);
}
int main(int argc, char *argv[])
{
g_test_init(&argc, &argv, NULL);
g_test_add_func("/qdist/none", test_none);
g_test_add_func("/qdist/single/empty", test_single_empty);
g_test_add_func("/qdist/single/full", test_single_full);
g_test_add_func("/qdist/binning/simple", test_bin_simple);
g_test_add_func("/qdist/binning/precision", test_bin_precision);
g_test_add_func("/qdist/binning/expand", test_bin_expand);
g_test_add_func("/qdist/binning/shrink", test_bin_shrink);
g_test_add_func("/qdist/pr", test_pr);
return g_test_run();
}

56
tests/test-qht-par.c Normal file
View File

@ -0,0 +1,56 @@
/*
* Copyright (C) 2016, Emilio G. Cota <cota@braap.org>
*
* License: GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*/
#include "qemu/osdep.h"
#include <glib.h>
#define TEST_QHT_STRING "tests/qht-bench 1>/dev/null 2>&1 -R -S0.1 -D10000 -N1 "
static void test_qht(int n_threads, int update_rate, int duration)
{
char *str;
int rc;
str = g_strdup_printf(TEST_QHT_STRING "-n %d -u %d -d %d",
n_threads, update_rate, duration);
rc = system(str);
g_free(str);
g_assert_cmpint(rc, ==, 0);
}
static void test_2th0u1s(void)
{
test_qht(2, 0, 1);
}
static void test_2th20u1s(void)
{
test_qht(2, 20, 1);
}
static void test_2th0u5s(void)
{
test_qht(2, 0, 5);
}
static void test_2th20u5s(void)
{
test_qht(2, 20, 5);
}
int main(int argc, char *argv[])
{
g_test_init(&argc, &argv, NULL);
if (g_test_quick()) {
g_test_add_func("/qht/parallel/2threads-0%updates-1s", test_2th0u1s);
g_test_add_func("/qht/parallel/2threads-20%updates-1s", test_2th20u1s);
} else {
g_test_add_func("/qht/parallel/2threads-0%updates-5s", test_2th0u5s);
g_test_add_func("/qht/parallel/2threads-20%updates-5s", test_2th20u5s);
}
return g_test_run();
}

159
tests/test-qht.c Normal file
View File

@ -0,0 +1,159 @@
/*
* Copyright (C) 2016, Emilio G. Cota <cota@braap.org>
*
* License: GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*/
#include "qemu/osdep.h"
#include <glib.h>
#include "qemu/qht.h"
#define N 5000
static struct qht ht;
static int32_t arr[N * 2];
static bool is_equal(const void *obj, const void *userp)
{
const int32_t *a = obj;
const int32_t *b = userp;
return *a == *b;
}
static void insert(int a, int b)
{
int i;
for (i = a; i < b; i++) {
uint32_t hash;
arr[i] = i;
hash = i;
qht_insert(&ht, &arr[i], hash);
}
}
static void rm(int init, int end)
{
int i;
for (i = init; i < end; i++) {
uint32_t hash;
hash = arr[i];
g_assert_true(qht_remove(&ht, &arr[i], hash));
}
}
static void check(int a, int b, bool expected)
{
struct qht_stats stats;
int i;
for (i = a; i < b; i++) {
void *p;
uint32_t hash;
int32_t val;
val = i;
hash = i;
p = qht_lookup(&ht, is_equal, &val, hash);
g_assert_true(!!p == expected);
}
qht_statistics_init(&ht, &stats);
if (stats.used_head_buckets) {
g_assert_cmpfloat(qdist_avg(&stats.chain), >=, 1.0);
}
g_assert_cmpuint(stats.head_buckets, >, 0);
qht_statistics_destroy(&stats);
}
static void count_func(struct qht *ht, void *p, uint32_t hash, void *userp)
{
unsigned int *curr = userp;
(*curr)++;
}
static void check_n(size_t expected)
{
struct qht_stats stats;
qht_statistics_init(&ht, &stats);
g_assert_cmpuint(stats.entries, ==, expected);
qht_statistics_destroy(&stats);
}
static void iter_check(unsigned int count)
{
unsigned int curr = 0;
qht_iter(&ht, count_func, &curr);
g_assert_cmpuint(curr, ==, count);
}
static void qht_do_test(unsigned int mode, size_t init_entries)
{
qht_init(&ht, 0, mode);
insert(0, N);
check(0, N, true);
check_n(N);
check(-N, -1, false);
iter_check(N);
rm(101, 102);
check_n(N - 1);
insert(N, N * 2);
check_n(N + N - 1);
rm(N, N * 2);
check_n(N - 1);
insert(101, 102);
check_n(N);
rm(10, 200);
check_n(N - 190);
insert(150, 200);
check_n(N - 190 + 50);
insert(10, 150);
check_n(N);
rm(1, 2);
check_n(N - 1);
qht_reset_size(&ht, 0);
check_n(0);
check(0, N, false);
qht_destroy(&ht);
}
static void qht_test(unsigned int mode)
{
qht_do_test(mode, 0);
qht_do_test(mode, 1);
qht_do_test(mode, 2);
qht_do_test(mode, 8);
qht_do_test(mode, 16);
qht_do_test(mode, 8192);
qht_do_test(mode, 16384);
}
static void test_default(void)
{
qht_test(0);
}
static void test_resize(void)
{
qht_test(QHT_MODE_AUTO_RESIZE);
}
int main(int argc, char *argv[])
{
g_test_init(&argc, &argv, NULL);
g_test_add_func("/qht/mode/default", test_default);
g_test_add_func("/qht/mode/resize", test_resize);
return g_test_run();
}

131
translate-all.c
View File

@ -735,6 +735,13 @@ static inline void code_gen_alloc(size_t tb_size)
qemu_mutex_init(&tcg_ctx.tb_ctx.tb_lock);
}
static void tb_htable_init(void)
{
unsigned int mode = QHT_MODE_AUTO_RESIZE;
qht_init(&tcg_ctx.tb_ctx.htable, CODE_GEN_HTABLE_SIZE, mode);
}
/* Must be called before using the QEMU cpus. 'tb_size' is the size
(in bytes) allocated to the translation buffer. Zero means default
size. */
@ -742,6 +749,7 @@ void tcg_exec_init(unsigned long tb_size)
{
cpu_gen_init();
page_init();
tb_htable_init();
code_gen_alloc(tb_size);
#if defined(CONFIG_SOFTMMU)
/* There's no guest base to take into account, so go ahead and
@ -846,7 +854,7 @@ void tb_flush(CPUState *cpu)
cpu->tb_flushed = true;
}
memset(tcg_ctx.tb_ctx.tb_phys_hash, 0, sizeof(tcg_ctx.tb_ctx.tb_phys_hash));
qht_reset_size(&tcg_ctx.tb_ctx.htable, CODE_GEN_HTABLE_SIZE);
page_flush_tb();
tcg_ctx.code_gen_ptr = tcg_ctx.code_gen_buffer;
@ -857,60 +865,46 @@ void tb_flush(CPUState *cpu)
#ifdef DEBUG_TB_CHECK
static void
do_tb_invalidate_check(struct qht *ht, void *p, uint32_t hash, void *userp)
{
TranslationBlock *tb = p;
target_ulong addr = *(target_ulong *)userp;
if (!(addr + TARGET_PAGE_SIZE <= tb->pc || addr >= tb->pc + tb->size)) {
printf("ERROR invalidate: address=" TARGET_FMT_lx
" PC=%08lx size=%04x\n", addr, (long)tb->pc, tb->size);
}
}
static void tb_invalidate_check(target_ulong address)
{
TranslationBlock *tb;
int i;
address &= TARGET_PAGE_MASK;
for (i = 0; i < CODE_GEN_PHYS_HASH_SIZE; i++) {
for (tb = tcg_ctx.tb_ctx.tb_phys_hash[i]; tb != NULL;
tb = tb->phys_hash_next) {
if (!(address + TARGET_PAGE_SIZE <= tb->pc ||
address >= tb->pc + tb->size)) {
printf("ERROR invalidate: address=" TARGET_FMT_lx
" PC=%08lx size=%04x\n",
address, (long)tb->pc, tb->size);
}
}
qht_iter(&tcg_ctx.tb_ctx.htable, do_tb_invalidate_check, &address);
}
static void
do_tb_page_check(struct qht *ht, void *p, uint32_t hash, void *userp)
{
TranslationBlock *tb = p;
int flags1, flags2;
flags1 = page_get_flags(tb->pc);
flags2 = page_get_flags(tb->pc + tb->size - 1);
if ((flags1 & PAGE_WRITE) || (flags2 & PAGE_WRITE)) {
printf("ERROR page flags: PC=%08lx size=%04x f1=%x f2=%x\n",
(long)tb->pc, tb->size, flags1, flags2);
}
}
/* verify that all the pages have correct rights for code */
static void tb_page_check(void)
{
TranslationBlock *tb;
int i, flags1, flags2;
for (i = 0; i < CODE_GEN_PHYS_HASH_SIZE; i++) {
for (tb = tcg_ctx.tb_ctx.tb_phys_hash[i]; tb != NULL;
tb = tb->phys_hash_next) {
flags1 = page_get_flags(tb->pc);
flags2 = page_get_flags(tb->pc + tb->size - 1);
if ((flags1 & PAGE_WRITE) || (flags2 & PAGE_WRITE)) {
printf("ERROR page flags: PC=%08lx size=%04x f1=%x f2=%x\n",
(long)tb->pc, tb->size, flags1, flags2);
}
}
}
qht_iter(&tcg_ctx.tb_ctx.htable, do_tb_page_check, NULL);
}
#endif
static inline void tb_hash_remove(TranslationBlock **ptb, TranslationBlock *tb)
{
TranslationBlock *tb1;
for (;;) {
tb1 = *ptb;
if (tb1 == tb) {
*ptb = tb1->phys_hash_next;
break;
}
ptb = &tb1->phys_hash_next;
}
}
static inline void tb_page_remove(TranslationBlock **ptb, TranslationBlock *tb)
{
TranslationBlock *tb1;
@ -992,13 +986,13 @@ void tb_phys_invalidate(TranslationBlock *tb, tb_page_addr_t page_addr)
{
CPUState *cpu;
PageDesc *p;
unsigned int h;
uint32_t h;
tb_page_addr_t phys_pc;
/* remove the TB from the hash list */
phys_pc = tb->page_addr[0] + (tb->pc & ~TARGET_PAGE_MASK);
h = tb_phys_hash_func(phys_pc);
tb_hash_remove(&tcg_ctx.tb_ctx.tb_phys_hash[h], tb);
h = tb_hash_func(phys_pc, tb->pc, tb->flags);
qht_remove(&tcg_ctx.tb_ctx.htable, tb, h);
/* remove the TB from the page list */
if (tb->page_addr[0] != page_addr) {
@ -1127,14 +1121,11 @@ static inline void tb_alloc_page(TranslationBlock *tb,
static void tb_link_page(TranslationBlock *tb, tb_page_addr_t phys_pc,
tb_page_addr_t phys_page2)
{
unsigned int h;
TranslationBlock **ptb;
uint32_t h;
/* add in the physical hash table */
h = tb_phys_hash_func(phys_pc);
ptb = &tcg_ctx.tb_ctx.tb_phys_hash[h];
tb->phys_hash_next = *ptb;
*ptb = tb;
/* add in the hash table */
h = tb_hash_func(phys_pc, tb->pc, tb->flags);
qht_insert(&tcg_ctx.tb_ctx.htable, tb, h);
/* add in the page list */
tb_alloc_page(tb, 0, phys_pc & TARGET_PAGE_MASK);
@ -1677,6 +1668,10 @@ void dump_exec_info(FILE *f, fprintf_function cpu_fprintf)
int i, target_code_size, max_target_code_size;
int direct_jmp_count, direct_jmp2_count, cross_page;
TranslationBlock *tb;
struct qht_stats hst;
uint32_t hgram_opts;
size_t hgram_bins;
char *hgram;
target_code_size = 0;
max_target_code_size = 0;
@ -1727,6 +1722,38 @@ void dump_exec_info(FILE *f, fprintf_function cpu_fprintf)
direct_jmp2_count,
tcg_ctx.tb_ctx.nb_tbs ? (direct_jmp2_count * 100) /
tcg_ctx.tb_ctx.nb_tbs : 0);
qht_statistics_init(&tcg_ctx.tb_ctx.htable, &hst);
cpu_fprintf(f, "TB hash buckets %zu/%zu (%0.2f%% head buckets used)\n",
hst.used_head_buckets, hst.head_buckets,
(double)hst.used_head_buckets / hst.head_buckets * 100);
hgram_opts = QDIST_PR_BORDER | QDIST_PR_LABELS;
hgram_opts |= QDIST_PR_100X | QDIST_PR_PERCENT;
if (qdist_xmax(&hst.occupancy) - qdist_xmin(&hst.occupancy) == 1) {
hgram_opts |= QDIST_PR_NODECIMAL;
}
hgram = qdist_pr(&hst.occupancy, 10, hgram_opts);
cpu_fprintf(f, "TB hash occupancy %0.2f%% avg chain occ. Histogram: %s\n",
qdist_avg(&hst.occupancy) * 100, hgram);
g_free(hgram);
hgram_opts = QDIST_PR_BORDER | QDIST_PR_LABELS;
hgram_bins = qdist_xmax(&hst.chain) - qdist_xmin(&hst.chain);
if (hgram_bins > 10) {
hgram_bins = 10;
} else {
hgram_bins = 0;
hgram_opts |= QDIST_PR_NODECIMAL | QDIST_PR_NOBINRANGE;
}
hgram = qdist_pr(&hst.chain, hgram_bins, hgram_opts);
cpu_fprintf(f, "TB hash avg chain %0.3f buckets. Histogram: %s\n",
qdist_avg(&hst.chain), hgram);
g_free(hgram);
qht_statistics_destroy(&hst);
cpu_fprintf(f, "\nStatistics:\n");
cpu_fprintf(f, "TB flush count %d\n", tcg_ctx.tb_ctx.tb_flush_count);
cpu_fprintf(f, "TB invalidate count %d\n",

2
util/Makefile.objs
View File

@ -32,3 +32,5 @@ util-obj-y += buffer.o
util-obj-y += timed-average.o
util-obj-y += base64.o
util-obj-y += log.o
util-obj-y += qdist.o
util-obj-y += qht.o

395
util/qdist.c Normal file
View File

@ -0,0 +1,395 @@
/*
* qdist.c - QEMU helpers for handling frequency distributions of data.
*
* Copyright (C) 2016, Emilio G. Cota <cota@braap.org>
*
* License: GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*/
#include "qemu/qdist.h"
#include <math.h>
#ifndef NAN
#define NAN (0.0 / 0.0)
#endif
void qdist_init(struct qdist *dist)
{
dist->entries = g_malloc(sizeof(*dist->entries));
dist->size = 1;
dist->n = 0;
}
void qdist_destroy(struct qdist *dist)
{
g_free(dist->entries);
}
static inline int qdist_cmp_double(double a, double b)
{
if (a > b) {
return 1;
} else if (a < b) {
return -1;
}
return 0;
}
static int qdist_cmp(const void *ap, const void *bp)
{
const struct qdist_entry *a = ap;
const struct qdist_entry *b = bp;
return qdist_cmp_double(a->x, b->x);
}
void qdist_add(struct qdist *dist, double x, long count)
{
struct qdist_entry *entry = NULL;
if (dist->n) {
struct qdist_entry e;
e.x = x;
entry = bsearch(&e, dist->entries, dist->n, sizeof(e), qdist_cmp);
}
if (entry) {
entry->count += count;
return;
}
if (unlikely(dist->n == dist->size)) {
dist->size *= 2;
dist->entries = g_realloc(dist->entries,
sizeof(*dist->entries) * (dist->size));
}
dist->n++;
entry = &dist->entries[dist->n - 1];
entry->x = x;
entry->count = count;
qsort(dist->entries, dist->n, sizeof(*entry), qdist_cmp);
}
void qdist_inc(struct qdist *dist, double x)
{
qdist_add(dist, x, 1);
}
/*
* Unicode for block elements. See:
* https://en.wikipedia.org/wiki/Block_Elements
*/
static const gunichar qdist_blocks[] = {
0x2581,
0x2582,
0x2583,
0x2584,
0x2585,
0x2586,
0x2587,
0x2588
};
#define QDIST_NR_BLOCK_CODES ARRAY_SIZE(qdist_blocks)
/*
* Print a distribution into a string.
*
* This function assumes that appropriate binning has been done on the input;
* see qdist_bin__internal() and qdist_pr_plain().
*
* Callers must free the returned string with g_free().
*/
static char *qdist_pr_internal(const struct qdist *dist)
{
double min, max;
GString *s = g_string_new("");
size_t i;
/* if only one entry, its printout will be either full or empty */
if (dist->n == 1) {
if (dist->entries[0].count) {
g_string_append_unichar(s, qdist_blocks[QDIST_NR_BLOCK_CODES - 1]);
} else {
g_string_append_c(s, ' ');
}
goto out;
}
/* get min and max counts */
min = dist->entries[0].count;
max = min;
for (i = 0; i < dist->n; i++) {
struct qdist_entry *e = &dist->entries[i];
if (e->count < min) {
min = e->count;
}
if (e->count > max) {
max = e->count;
}
}
for (i = 0; i < dist->n; i++) {
struct qdist_entry *e = &dist->entries[i];
int index;
/* make an exception with 0; instead of using block[0], print a space */
if (e->count) {
/* divide first to avoid loss of precision when e->count == max */
index = (e->count - min) / (max - min) * (QDIST_NR_BLOCK_CODES - 1);
g_string_append_unichar(s, qdist_blocks[index]);
} else {
g_string_append_c(s, ' ');
}
}
out:
return g_string_free(s, FALSE);
}
/*
* Bin the distribution in @from into @n bins of consecutive, non-overlapping
* intervals, copying the result to @to.
*
* This function is internal to qdist: only this file and test code should
* ever call it.
*
* Note: calling this function on an already-binned qdist is a bug.
*
* If @n == 0 or @from->n == 1, use @from->n.
*/
void qdist_bin__internal(struct qdist *to, const struct qdist *from, size_t n)
{
double xmin, xmax;
double step;
size_t i, j;
qdist_init(to);
if (from->n == 0) {
return;
}
if (n == 0 || from->n == 1) {
n = from->n;
}
/* set equally-sized bins between @from's left and right */
xmin = qdist_xmin(from);
xmax = qdist_xmax(from);
step = (xmax - xmin) / n;
if (n == from->n) {
/* if @from's entries are equally spaced, no need to re-bin */
for (i = 0; i < from->n; i++) {
if (from->entries[i].x != xmin + i * step) {
goto rebin;
}
}
/* they're equally spaced, so copy the dist and bail out */
to->entries = g_new(struct qdist_entry, from->n);
to->n = from->n;
memcpy(to->entries, from->entries, sizeof(*to->entries) * to->n);
return;
}
rebin:
j = 0;
for (i = 0; i < n; i++) {
double x;
double left, right;
left = xmin + i * step;
right = xmin + (i + 1) * step;
/* Add x, even if it might not get any counts later */
x = left;
qdist_add(to, x, 0);
/*
* To avoid double-counting we capture [left, right) ranges, except for
* the righmost bin, which captures a [left, right] range.
*/
while (j < from->n && (from->entries[j].x < right || i == n - 1)) {
struct qdist_entry *o = &from->entries[j];
qdist_add(to, x, o->count);
j++;
}
}
}
/*
* Print @dist into a string, after re-binning it into @n bins of consecutive,
* non-overlapping intervals.
*
* If @n == 0, use @orig->n.
*
* Callers must free the returned string with g_free().
*/
char *qdist_pr_plain(const struct qdist *dist, size_t n)
{
struct qdist binned;
char *ret;
if (dist->n == 0) {
return NULL;
}
qdist_bin__internal(&binned, dist, n);
ret = qdist_pr_internal(&binned);
qdist_destroy(&binned);
return ret;
}
static char *qdist_pr_label(const struct qdist *dist, size_t n_bins,
uint32_t opt, bool is_left)
{
const char *percent;
const char *lparen;
const char *rparen;
GString *s;
double x1, x2, step;
double x;
double n;
int dec;
s = g_string_new("");
if (!(opt & QDIST_PR_LABELS)) {
goto out;
}
dec = opt & QDIST_PR_NODECIMAL ? 0 : 1;
percent = opt & QDIST_PR_PERCENT ? "%" : "";
n = n_bins ? n_bins : dist->n;
x = is_left ? qdist_xmin(dist) : qdist_xmax(dist);
step = (qdist_xmax(dist) - qdist_xmin(dist)) / n;
if (opt & QDIST_PR_100X) {
x *= 100.0;
step *= 100.0;
}
if (opt & QDIST_PR_NOBINRANGE) {
lparen = rparen = "";
x1 = x;
x2 = x; /* unnecessary, but a dumb compiler might not figure it out */
} else {
lparen = "[";
rparen = is_left ? ")" : "]";
if (is_left) {
x1 = x;
x2 = x + step;
} else {
x1 = x - step;
x2 = x;
}
}
g_string_append_printf(s, "%s%.*f", lparen, dec, x1);
if (!(opt & QDIST_PR_NOBINRANGE)) {
g_string_append_printf(s, ",%.*f%s", dec, x2, rparen);
}
g_string_append(s, percent);
out:
return g_string_free(s, FALSE);
}
/*
* Print the distribution's histogram into a string.
*
* See also: qdist_pr_plain().
*
* Callers must free the returned string with g_free().
*/
char *qdist_pr(const struct qdist *dist, size_t n_bins, uint32_t opt)
{
const char *border = opt & QDIST_PR_BORDER ? "|" : "";
char *llabel, *rlabel;
char *hgram;
GString *s;
if (dist->n == 0) {
return NULL;
}
s = g_string_new("");
llabel = qdist_pr_label(dist, n_bins, opt, true);
rlabel = qdist_pr_label(dist, n_bins, opt, false);
hgram = qdist_pr_plain(dist, n_bins);
g_string_append_printf(s, "%s%s%s%s%s",
llabel, border, hgram, border, rlabel);
g_free(llabel);
g_free(rlabel);
g_free(hgram);
return g_string_free(s, FALSE);
}
static inline double qdist_x(const struct qdist *dist, int index)
{
if (dist->n == 0) {
return NAN;
}
return dist->entries[index].x;
}
double qdist_xmin(const struct qdist *dist)
{
return qdist_x(dist, 0);
}
double qdist_xmax(const struct qdist *dist)
{
return qdist_x(dist, dist->n - 1);
}
size_t qdist_unique_entries(const struct qdist *dist)
{
return dist->n;
}
unsigned long qdist_sample_count(const struct qdist *dist)
{
unsigned long count = 0;
size_t i;
for (i = 0; i < dist->n; i++) {
struct qdist_entry *e = &dist->entries[i];
count += e->count;
}
return count;
}
static double qdist_pairwise_avg(const struct qdist *dist, size_t index,
size_t n, unsigned long count)
{
/* amortize the recursion by using a base case > 2 */
if (n <= 8) {
size_t i;
double ret = 0;
for (i = 0; i < n; i++) {
struct qdist_entry *e = &dist->entries[index + i];
ret += e->x * e->count / count;
}
return ret;
} else {
size_t n2 = n / 2;
return qdist_pairwise_avg(dist, index, n2, count) +
qdist_pairwise_avg(dist, index + n2, n - n2, count);
}
}
double qdist_avg(const struct qdist *dist)
{
unsigned long count;
count = qdist_sample_count(dist);
if (!count) {
return NAN;
}
return qdist_pairwise_avg(dist, 0, dist->n, count);
}

833
util/qht.c Normal file
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/*
* qht.c - QEMU Hash Table, designed to scale for read-mostly workloads.
*
* Copyright (C) 2016, Emilio G. Cota <cota@braap.org>
*
* License: GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*
* Assumptions:
* - NULL cannot be inserted/removed as a pointer value.
* - Trying to insert an already-existing hash-pointer pair is OK. However,
* it is not OK to insert into the same hash table different hash-pointer
* pairs that have the same pointer value, but not the hashes.
* - Lookups are performed under an RCU read-critical section; removals
* must wait for a grace period to elapse before freeing removed objects.
*
* Features:
* - Reads (i.e. lookups and iterators) can be concurrent with other reads.
* Lookups that are concurrent with writes to the same bucket will retry
* via a seqlock; iterators acquire all bucket locks and therefore can be
* concurrent with lookups and are serialized wrt writers.
* - Writes (i.e. insertions/removals) can be concurrent with writes to
* different buckets; writes to the same bucket are serialized through a lock.
* - Optional auto-resizing: the hash table resizes up if the load surpasses
* a certain threshold. Resizing is done concurrently with readers; writes
* are serialized with the resize operation.
*
* The key structure is the bucket, which is cacheline-sized. Buckets
* contain a few hash values and pointers; the u32 hash values are stored in
* full so that resizing is fast. Having this structure instead of directly
* chaining items has two advantages:
* - Failed lookups fail fast, and touch a minimum number of cache lines.
* - Resizing the hash table with concurrent lookups is easy.
*
* There are two types of buckets:
* 1. "head" buckets are the ones allocated in the array of buckets in qht_map.
* 2. all "non-head" buckets (i.e. all others) are members of a chain that
* starts from a head bucket.
* Note that the seqlock and spinlock of a head bucket applies to all buckets
* chained to it; these two fields are unused in non-head buckets.
*
* On removals, we move the last valid item in the chain to the position of the
* just-removed entry. This makes lookups slightly faster, since the moment an
* invalid entry is found, the (failed) lookup is over.
*
* Resizing is done by taking all bucket spinlocks (so that no other writers can
* race with us) and then copying all entries into a new hash map. Then, the
* ht->map pointer is set, and the old map is freed once no RCU readers can see
* it anymore.
*
* Writers check for concurrent resizes by comparing ht->map before and after
* acquiring their bucket lock. If they don't match, a resize has occured
* while the bucket spinlock was being acquired.
*
* Related Work:
* - Idea of cacheline-sized buckets with full hashes taken from:
* David, Guerraoui & Trigonakis, "Asynchronized Concurrency:
* The Secret to Scaling Concurrent Search Data Structures", ASPLOS'15.
* - Why not RCU-based hash tables? They would allow us to get rid of the
* seqlock, but resizing would take forever since RCU read critical
* sections in QEMU take quite a long time.
* More info on relativistic hash tables:
* + Triplett, McKenney & Walpole, "Resizable, Scalable, Concurrent Hash
* Tables via Relativistic Programming", USENIX ATC'11.
* + Corbet, "Relativistic hash tables, part 1: Algorithms", @ lwn.net, 2014.
* https://lwn.net/Articles/612021/
*/
#include "qemu/qht.h"
#include "qemu/atomic.h"
#include "qemu/rcu.h"
//#define QHT_DEBUG
/*
* We want to avoid false sharing of cache lines. Most systems have 64-byte
* cache lines so we go with it for simplicity.
*
* Note that systems with smaller cache lines will be fine (the struct is
* almost 64-bytes); systems with larger cache lines might suffer from
* some false sharing.
*/
#define QHT_BUCKET_ALIGN 64
/* define these to keep sizeof(qht_bucket) within QHT_BUCKET_ALIGN */
#if HOST_LONG_BITS == 32
#define QHT_BUCKET_ENTRIES 6
#else /* 64-bit */
#define QHT_BUCKET_ENTRIES 4
#endif
/*
* Note: reading partially-updated pointers in @pointers could lead to
* segfaults. We thus access them with atomic_read/set; this guarantees
* that the compiler makes all those accesses atomic. We also need the
* volatile-like behavior in atomic_read, since otherwise the compiler
* might refetch the pointer.
* atomic_read's are of course not necessary when the bucket lock is held.
*
* If both ht->lock and b->lock are grabbed, ht->lock should always
* be grabbed first.
*/
struct qht_bucket {
QemuSpin lock;
QemuSeqLock sequence;
uint32_t hashes[QHT_BUCKET_ENTRIES];
void *pointers[QHT_BUCKET_ENTRIES];
struct qht_bucket *next;
} QEMU_ALIGNED(QHT_BUCKET_ALIGN);
QEMU_BUILD_BUG_ON(sizeof(struct qht_bucket) > QHT_BUCKET_ALIGN);
/**
* struct qht_map - structure to track an array of buckets
* @rcu: used by RCU. Keep it as the top field in the struct to help valgrind
* find the whole struct.
* @buckets: array of head buckets. It is constant once the map is created.
* @n_buckets: number of head buckets. It is constant once the map is created.
* @n_added_buckets: number of added (i.e. "non-head") buckets
* @n_added_buckets_threshold: threshold to trigger an upward resize once the
* number of added buckets surpasses it.
*
* Buckets are tracked in what we call a "map", i.e. this structure.
*/
struct qht_map {
struct rcu_head rcu;
struct qht_bucket *buckets;
size_t n_buckets;
size_t n_added_buckets;
size_t n_added_buckets_threshold;
};
/* trigger a resize when n_added_buckets > n_buckets / div */
#define QHT_NR_ADDED_BUCKETS_THRESHOLD_DIV 8
static void qht_do_resize(struct qht *ht, struct qht_map *new);
static void qht_grow_maybe(struct qht *ht);
#ifdef QHT_DEBUG
#define qht_debug_assert(X) do { assert(X); } while (0)
static void qht_bucket_debug__locked(struct qht_bucket *b)
{
bool seen_empty = false;
bool corrupt = false;
int i;
do {
for (i = 0; i < QHT_BUCKET_ENTRIES; i++) {
if (b->pointers[i] == NULL) {
seen_empty = true;
continue;
}
if (seen_empty) {
fprintf(stderr, "%s: b: %p, pos: %i, hash: 0x%x, p: %p\n",
__func__, b, i, b->hashes[i], b->pointers[i]);
corrupt = true;
}
}
b = b->next;
} while (b);
qht_debug_assert(!corrupt);
}
static void qht_map_debug__all_locked(struct qht_map *map)
{
int i;
for (i = 0; i < map->n_buckets; i++) {
qht_bucket_debug__locked(&map->buckets[i]);
}
}
#else
#define qht_debug_assert(X) do { (void)(X); } while (0)
static inline void qht_bucket_debug__locked(struct qht_bucket *b)
{ }
static inline void qht_map_debug__all_locked(struct qht_map *map)
{ }
#endif /* QHT_DEBUG */
static inline size_t qht_elems_to_buckets(size_t n_elems)
{
return pow2ceil(n_elems / QHT_BUCKET_ENTRIES);
}
static inline void qht_head_init(struct qht_bucket *b)
{
memset(b, 0, sizeof(*b));
qemu_spin_init(&b->lock);
seqlock_init(&b->sequence);
}
static inline
struct qht_bucket *qht_map_to_bucket(struct qht_map *map, uint32_t hash)
{
return &map->buckets[hash & (map->n_buckets - 1)];
}
/* acquire all bucket locks from a map */
static void qht_map_lock_buckets(struct qht_map *map)
{
size_t i;
for (i = 0; i < map->n_buckets; i++) {
struct qht_bucket *b = &map->buckets[i];
qemu_spin_lock(&b->lock);
}
}
static void qht_map_unlock_buckets(struct qht_map *map)
{
size_t i;
for (i = 0; i < map->n_buckets; i++) {
struct qht_bucket *b = &map->buckets[i];
qemu_spin_unlock(&b->lock);
}
}
/*
* Call with at least a bucket lock held.
* @map should be the value read before acquiring the lock (or locks).
*/
static inline bool qht_map_is_stale__locked(struct qht *ht, struct qht_map *map)
{
return map != ht->map;
}
/*
* Grab all bucket locks, and set @pmap after making sure the map isn't stale.
*
* Pairs with qht_map_unlock_buckets(), hence the pass-by-reference.
*
* Note: callers cannot have ht->lock held.
*/
static inline
void qht_map_lock_buckets__no_stale(struct qht *ht, struct qht_map **pmap)
{
struct qht_map *map;
map = atomic_rcu_read(&ht->map);
qht_map_lock_buckets(map);
if (likely(!qht_map_is_stale__locked(ht, map))) {
*pmap = map;
return;
}
qht_map_unlock_buckets(map);
/* we raced with a resize; acquire ht->lock to see the updated ht->map */
qemu_mutex_lock(&ht->lock);
map = ht->map;
qht_map_lock_buckets(map);
qemu_mutex_unlock(&ht->lock);
*pmap = map;
return;
}
/*
* Get a head bucket and lock it, making sure its parent map is not stale.
* @pmap is filled with a pointer to the bucket's parent map.
*
* Unlock with qemu_spin_unlock(&b->lock).
*
* Note: callers cannot have ht->lock held.
*/
static inline
struct qht_bucket *qht_bucket_lock__no_stale(struct qht *ht, uint32_t hash,
struct qht_map **pmap)
{
struct qht_bucket *b;
struct qht_map *map;
map = atomic_rcu_read(&ht->map);
b = qht_map_to_bucket(map, hash);
qemu_spin_lock(&b->lock);
if (likely(!qht_map_is_stale__locked(ht, map))) {
*pmap = map;
return b;
}
qemu_spin_unlock(&b->lock);
/* we raced with a resize; acquire ht->lock to see the updated ht->map */
qemu_mutex_lock(&ht->lock);
map = ht->map;
b = qht_map_to_bucket(map, hash);
qemu_spin_lock(&b->lock);
qemu_mutex_unlock(&ht->lock);
*pmap = map;
return b;
}
static inline bool qht_map_needs_resize(struct qht_map *map)
{
return atomic_read(&map->n_added_buckets) > map->n_added_buckets_threshold;
}
static inline void qht_chain_destroy(struct qht_bucket *head)
{
struct qht_bucket *curr = head->next;
struct qht_bucket *prev;
while (curr) {
prev = curr;
curr = curr->next;
qemu_vfree(prev);
}
}
/* pass only an orphan map */
static void qht_map_destroy(struct qht_map *map)
{
size_t i;
for (i = 0; i < map->n_buckets; i++) {
qht_chain_destroy(&map->buckets[i]);
}
qemu_vfree(map->buckets);
g_free(map);
}
static struct qht_map *qht_map_create(size_t n_buckets)
{
struct qht_map *map;
size_t i;
map = g_malloc(sizeof(*map));
map->n_buckets = n_buckets;
map->n_added_buckets = 0;
map->n_added_buckets_threshold = n_buckets /
QHT_NR_ADDED_BUCKETS_THRESHOLD_DIV;
/* let tiny hash tables to at least add one non-head bucket */
if (unlikely(map->n_added_buckets_threshold == 0)) {
map->n_added_buckets_threshold = 1;
}
map->buckets = qemu_memalign(QHT_BUCKET_ALIGN,
sizeof(*map->buckets) * n_buckets);
for (i = 0; i < n_buckets; i++) {
qht_head_init(&map->buckets[i]);
}
return map;
}
void qht_init(struct qht *ht, size_t n_elems, unsigned int mode)
{
struct qht_map *map;
size_t n_buckets = qht_elems_to_buckets(n_elems);
ht->mode = mode;
qemu_mutex_init(&ht->lock);
map = qht_map_create(n_buckets);
atomic_rcu_set(&ht->map, map);
}
/* call only when there are no readers/writers left */
void qht_destroy(struct qht *ht)
{
qht_map_destroy(ht->map);
memset(ht, 0, sizeof(*ht));
}
static void qht_bucket_reset__locked(struct qht_bucket *head)
{
struct qht_bucket *b = head;
int i;
seqlock_write_begin(&head->sequence);
do {
for (i = 0; i < QHT_BUCKET_ENTRIES; i++) {
if (b->pointers[i] == NULL) {
goto done;
}
b->hashes[i] = 0;
atomic_set(&b->pointers[i], NULL);
}
b = b->next;
} while (b);
done:
seqlock_write_end(&head->sequence);
}
/* call with all bucket locks held */
static void qht_map_reset__all_locked(struct qht_map *map)
{
size_t i;
for (i = 0; i < map->n_buckets; i++) {
qht_bucket_reset__locked(&map->buckets[i]);
}
qht_map_debug__all_locked(map);
}
void qht_reset(struct qht *ht)
{
struct qht_map *map;
qht_map_lock_buckets__no_stale(ht, &map);
qht_map_reset__all_locked(map);
qht_map_unlock_buckets(map);
}
bool qht_reset_size(struct qht *ht, size_t n_elems)
{
struct qht_map *new;
struct qht_map *map;
size_t n_buckets;
bool resize = false;
n_buckets = qht_elems_to_buckets(n_elems);
qemu_mutex_lock(&ht->lock);
map = ht->map;
if (n_buckets != map->n_buckets) {
new = qht_map_create(n_buckets);
resize = true;
}
qht_map_lock_buckets(map);
qht_map_reset__all_locked(map);
if (resize) {
qht_do_resize(ht, new);
}
qht_map_unlock_buckets(map);
qemu_mutex_unlock(&ht->lock);
return resize;
}
static inline
void *qht_do_lookup(struct qht_bucket *head, qht_lookup_func_t func,
const void *userp, uint32_t hash)
{
struct qht_bucket *b = head;
int i;
do {
for (i = 0; i < QHT_BUCKET_ENTRIES; i++) {
if (b->hashes[i] == hash) {
void *p = atomic_read(&b->pointers[i]);
if (likely(p) && likely(func(p, userp))) {
return p;
}
}
}
b = atomic_rcu_read(&b->next);
} while (b);
return NULL;
}
static __attribute__((noinline))
void *qht_lookup__slowpath(struct qht_bucket *b, qht_lookup_func_t func,
const void *userp, uint32_t hash)
{
unsigned int version;
void *ret;
do {
version = seqlock_read_begin(&b->sequence);
ret = qht_do_lookup(b, func, userp, hash);
} while (seqlock_read_retry(&b->sequence, version));
return ret;
}
void *qht_lookup(struct qht *ht, qht_lookup_func_t func, const void *userp,
uint32_t hash)
{
struct qht_bucket *b;
struct qht_map *map;
unsigned int version;
void *ret;
map = atomic_rcu_read(&ht->map);
b = qht_map_to_bucket(map, hash);
version = seqlock_read_begin(&b->sequence);
ret = qht_do_lookup(b, func, userp, hash);
if (likely(!seqlock_read_retry(&b->sequence, version))) {
return ret;
}
/*
* Removing the do/while from the fastpath gives a 4% perf. increase when
* running a 100%-lookup microbenchmark.
*/
return qht_lookup__slowpath(b, func, userp, hash);
}
/* call with head->lock held */
static bool qht_insert__locked(struct qht *ht, struct qht_map *map,
struct qht_bucket *head, void *p, uint32_t hash,
bool *needs_resize)
{
struct qht_bucket *b = head;
struct qht_bucket *prev = NULL;
struct qht_bucket *new = NULL;
int i;
do {
for (i = 0; i < QHT_BUCKET_ENTRIES; i++) {
if (b->pointers[i]) {
if (unlikely(b->pointers[i] == p)) {
return false;
}
} else {
goto found;
}
}
prev = b;
b = b->next;
} while (b);
b = qemu_memalign(QHT_BUCKET_ALIGN, sizeof(*b));
memset(b, 0, sizeof(*b));
new = b;
i = 0;
atomic_inc(&map->n_added_buckets);
if (unlikely(qht_map_needs_resize(map)) && needs_resize) {
*needs_resize = true;
}
found:
/* found an empty key: acquire the seqlock and write */
seqlock_write_begin(&head->sequence);
if (new) {
atomic_rcu_set(&prev->next, b);
}
b->hashes[i] = hash;
atomic_set(&b->pointers[i], p);
seqlock_write_end(&head->sequence);
return true;
}
static __attribute__((noinline)) void qht_grow_maybe(struct qht *ht)
{
struct qht_map *map;
/*
* If the lock is taken it probably means there's an ongoing resize,
* so bail out.
*/
if (qemu_mutex_trylock(&ht->lock)) {
return;
}
map = ht->map;
/* another thread might have just performed the resize we were after */
if (qht_map_needs_resize(map)) {
struct qht_map *new = qht_map_create(map->n_buckets * 2);
qht_map_lock_buckets(map);
qht_do_resize(ht, new);
qht_map_unlock_buckets(map);
}
qemu_mutex_unlock(&ht->lock);
}
bool qht_insert(struct qht *ht, void *p, uint32_t hash)
{
struct qht_bucket *b;
struct qht_map *map;
bool needs_resize = false;
bool ret;
/* NULL pointers are not supported */
qht_debug_assert(p);
b = qht_bucket_lock__no_stale(ht, hash, &map);
ret = qht_insert__locked(ht, map, b, p, hash, &needs_resize);
qht_bucket_debug__locked(b);
qemu_spin_unlock(&b->lock);
if (unlikely(needs_resize) && ht->mode & QHT_MODE_AUTO_RESIZE) {
qht_grow_maybe(ht);
}
return ret;
}
static inline bool qht_entry_is_last(struct qht_bucket *b, int pos)
{
if (pos == QHT_BUCKET_ENTRIES - 1) {
if (b->next == NULL) {
return true;
}
return b->next->pointers[0] == NULL;
}
return b->pointers[pos + 1] == NULL;
}
static void
qht_entry_move(struct qht_bucket *to, int i, struct qht_bucket *from, int j)
{
qht_debug_assert(!(to == from && i == j));
qht_debug_assert(to->pointers[i]);
qht_debug_assert(from->pointers[j]);
to->hashes[i] = from->hashes[j];
atomic_set(&to->pointers[i], from->pointers[j]);
from->hashes[j] = 0;
atomic_set(&from->pointers[j], NULL);
}
/*
* Find the last valid entry in @head, and swap it with @orig[pos], which has
* just been invalidated.
*/
static inline void qht_bucket_remove_entry(struct qht_bucket *orig, int pos)
{
struct qht_bucket *b = orig;
struct qht_bucket *prev = NULL;
int i;
if (qht_entry_is_last(orig, pos)) {
orig->hashes[pos] = 0;
atomic_set(&orig->pointers[pos], NULL);
return;
}
do {
for (i = 0; i < QHT_BUCKET_ENTRIES; i++) {
if (b->pointers[i]) {
continue;
}
if (i > 0) {
return qht_entry_move(orig, pos, b, i - 1);
}
qht_debug_assert(prev);
return qht_entry_move(orig, pos, prev, QHT_BUCKET_ENTRIES - 1);
}
prev = b;
b = b->next;
} while (b);
/* no free entries other than orig[pos], so swap it with the last one */
qht_entry_move(orig, pos, prev, QHT_BUCKET_ENTRIES - 1);
}
/* call with b->lock held */
static inline
bool qht_remove__locked(struct qht_map *map, struct qht_bucket *head,
const void *p, uint32_t hash)
{
struct qht_bucket *b = head;
int i;
do {
for (i = 0; i < QHT_BUCKET_ENTRIES; i++) {
void *q = b->pointers[i];
if (unlikely(q == NULL)) {
return false;
}
if (q == p) {
qht_debug_assert(b->hashes[i] == hash);
seqlock_write_begin(&head->sequence);
qht_bucket_remove_entry(b, i);
seqlock_write_end(&head->sequence);
return true;
}
}
b = b->next;
} while (b);
return false;
}
bool qht_remove(struct qht *ht, const void *p, uint32_t hash)
{
struct qht_bucket *b;
struct qht_map *map;
bool ret;
/* NULL pointers are not supported */
qht_debug_assert(p);
b = qht_bucket_lock__no_stale(ht, hash, &map);
ret = qht_remove__locked(map, b, p, hash);
qht_bucket_debug__locked(b);
qemu_spin_unlock(&b->lock);
return ret;
}
static inline void qht_bucket_iter(struct qht *ht, struct qht_bucket *b,
qht_iter_func_t func, void *userp)
{
int i;
do {
for (i = 0; i < QHT_BUCKET_ENTRIES; i++) {
if (b->pointers[i] == NULL) {
return;
}
func(ht, b->pointers[i], b->hashes[i], userp);
}
b = b->next;
} while (b);
}
/* call with all of the map's locks held */
static inline void qht_map_iter__all_locked(struct qht *ht, struct qht_map *map,
qht_iter_func_t func, void *userp)
{
size_t i;
for (i = 0; i < map->n_buckets; i++) {
qht_bucket_iter(ht, &map->buckets[i], func, userp);
}
}
void qht_iter(struct qht *ht, qht_iter_func_t func, void *userp)
{
struct qht_map *map;
map = atomic_rcu_read(&ht->map);
qht_map_lock_buckets(map);
/* Note: ht here is merely for carrying ht->mode; ht->map won't be read */
qht_map_iter__all_locked(ht, map, func, userp);
qht_map_unlock_buckets(map);
}
static void qht_map_copy(struct qht *ht, void *p, uint32_t hash, void *userp)
{
struct qht_map *new = userp;
struct qht_bucket *b = qht_map_to_bucket(new, hash);
/* no need to acquire b->lock because no thread has seen this map yet */
qht_insert__locked(ht, new, b, p, hash, NULL);
}
/*
* Call with ht->lock and all bucket locks held.
*
* Creating the @new map here would add unnecessary delay while all the locks
* are held--holding up the bucket locks is particularly bad, since no writes
* can occur while these are held. Thus, we let callers create the new map,
* hopefully without the bucket locks held.
*/
static void qht_do_resize(struct qht *ht, struct qht_map *new)
{
struct qht_map *old;
old = ht->map;
g_assert_cmpuint(new->n_buckets, !=, old->n_buckets);
qht_map_iter__all_locked(ht, old, qht_map_copy, new);
qht_map_debug__all_locked(new);
atomic_rcu_set(&ht->map, new);
call_rcu(old, qht_map_destroy, rcu);
}
bool qht_resize(struct qht *ht, size_t n_elems)
{
size_t n_buckets = qht_elems_to_buckets(n_elems);
size_t ret = false;
qemu_mutex_lock(&ht->lock);
if (n_buckets != ht->map->n_buckets) {
struct qht_map *new;
struct qht_map *old = ht->map;
new = qht_map_create(n_buckets);
qht_map_lock_buckets(old);
qht_do_resize(ht, new);
qht_map_unlock_buckets(old);
ret = true;
}
qemu_mutex_unlock(&ht->lock);
return ret;
}
/* pass @stats to qht_statistics_destroy() when done */
void qht_statistics_init(struct qht *ht, struct qht_stats *stats)
{
struct qht_map *map;
int i;
map = atomic_rcu_read(&ht->map);
stats->head_buckets = map->n_buckets;
stats->used_head_buckets = 0;
stats->entries = 0;
qdist_init(&stats->chain);
qdist_init(&stats->occupancy);
for (i = 0; i < map->n_buckets; i++) {
struct qht_bucket *head = &map->buckets[i];
struct qht_bucket *b;
unsigned int version;
size_t buckets;
size_t entries;
int j;
do {
version = seqlock_read_begin(&head->sequence);
buckets = 0;
entries = 0;
b = head;
do {
for (j = 0; j < QHT_BUCKET_ENTRIES; j++) {
if (atomic_read(&b->pointers[j]) == NULL) {
break;
}
entries++;
}
buckets++;
b = atomic_rcu_read(&b->next);
} while (b);
} while (seqlock_read_retry(&head->sequence, version));
if (entries) {
qdist_inc(&stats->chain, buckets);
qdist_inc(&stats->occupancy,
(double)entries / QHT_BUCKET_ENTRIES / buckets);
stats->used_head_buckets++;
stats->entries += entries;
} else {
qdist_inc(&stats->occupancy, 0);
}
}
}
void qht_statistics_destroy(struct qht_stats *stats)
{
qdist_destroy(&stats->occupancy);
qdist_destroy(&stats->chain);
}