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qht: require a default comparison function

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qht_lookup now uses the default cmp function. qht_lookup_custom is defined
to retain the old behaviour, that is a cmp function is explicitly provided.

qht_insert will gain use of the default cmp in the next patch.

Note that we move qht_lookup_custom's @func to be the last argument,
which makes the new qht_lookup as simple as possible.
Instead of this (i.e. keeping @func 2nd):
0000000000010750 <qht_lookup>:
   10750:       89 d1                   mov    %edx,%ecx
   10752:       48 89 f2                mov    %rsi,%rdx
   10755:       48 8b 77 08             mov    0x8(%rdi),%rsi
   10759:       e9 22 ff ff ff          jmpq   10680 <qht_lookup_custom>
   1075e:       66 90                   xchg   %ax,%ax

We get:
0000000000010740 <qht_lookup>:
   10740:       48 8b 4f 08             mov    0x8(%rdi),%rcx
   10744:       e9 37 ff ff ff          jmpq   10680 <qht_lookup_custom>
   10749:       0f 1f 80 00 00 00 00    nopl   0x0(%rax)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Emilio G. Cota 2017-07-11 18:47:38 -04:00 committed by Richard Henderson
parent 1019242af1
commit 61b8cef1d4
6 changed files with 65 additions and 23 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
accel/tcg/cpu-exec.c
View File

@ -295,7 +295,7 @@ struct tb_desc {
uint32_t trace_vcpu_dstate;
};
static bool tb_cmp(const void *p, const void *d)
static bool tb_lookup_cmp(const void *p, const void *d)
{
const TranslationBlock *tb = p;
const struct tb_desc *desc = d;
@ -340,7 +340,7 @@ TranslationBlock *tb_htable_lookup(CPUState *cpu, target_ulong 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, cf_mask, *cpu->trace_dstate);
return qht_lookup(&tb_ctx.htable, tb_cmp, &desc, h);
return qht_lookup_custom(&tb_ctx.htable, &desc, h, tb_lookup_cmp);
}
void tb_set_jmp_target(TranslationBlock *tb, int n, uintptr_t addr)

16
accel/tcg/translate-all.c
View File

@ -782,11 +782,25 @@ static inline void code_gen_alloc(size_t tb_size)
qemu_mutex_init(&tb_ctx.tb_lock);
}
static bool tb_cmp(const void *ap, const void *bp)
{
const TranslationBlock *a = ap;
const TranslationBlock *b = bp;
return a->pc == b->pc &&
a->cs_base == b->cs_base &&
a->flags == b->flags &&
(tb_cflags(a) & CF_HASH_MASK) == (tb_cflags(b) & CF_HASH_MASK) &&
a->trace_vcpu_dstate == b->trace_vcpu_dstate &&
a->page_addr[0] == b->page_addr[0] &&
a->page_addr[1] == b->page_addr[1];
}
static void tb_htable_init(void)
{
unsigned int mode = QHT_MODE_AUTO_RESIZE;
qht_init(&tb_ctx.htable, CODE_GEN_HTABLE_SIZE, mode);
qht_init(&tb_ctx.htable, tb_cmp, CODE_GEN_HTABLE_SIZE, mode);
}
/* Must be called before using the QEMU cpus. 'tb_size' is the size

25
include/qemu/qht.h
View File

@ -11,8 +11,11 @@
#include "qemu/thread.h"
#include "qemu/qdist.h"
typedef bool (*qht_cmp_func_t)(const void *a, const void *b);
struct qht {
struct qht_map *map;
qht_cmp_func_t cmp;
QemuMutex lock; /* serializes setters of ht->map */
unsigned int mode;
};
@ -47,10 +50,12 @@ typedef void (*qht_iter_func_t)(struct qht *ht, void *p, uint32_t h, void *up);
/**
* qht_init - Initialize a QHT
* @ht: QHT to be initialized
* @cmp: default comparison function. Cannot be NULL.
* @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);
void qht_init(struct qht *ht, qht_cmp_func_t cmp, size_t n_elems,
unsigned int mode);
/**
* qht_destroy - destroy a previously initialized QHT
@ -78,11 +83,11 @@ void qht_destroy(struct qht *ht);
bool qht_insert(struct qht *ht, void *p, uint32_t hash);
/**
* qht_lookup - Look up a pointer in a QHT
* qht_lookup_custom - Look up a pointer using a custom comparison function.
* @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
* @func: function to compare existing pointers against @userp
*
* Needs to be called under an RCU read-critical section.
*
@ -94,8 +99,18 @@ bool qht_insert(struct qht *ht, void *p, uint32_t hash);
* 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);
void *qht_lookup_custom(struct qht *ht, const void *userp, uint32_t hash,
qht_lookup_func_t func);
/**
* qht_lookup - Look up a pointer in a QHT
* @ht: QHT to be looked up
* @userp: pointer to pass to the comparison function
* @hash: hash of the pointer to be looked up
*
* Calls qht_lookup_custom() using @ht's default comparison function.
*/
void *qht_lookup(struct qht *ht, const void *userp, uint32_t hash);
/**
* qht_remove - remove a pointer from the hash table

14
tests/qht-bench.c
View File

@ -93,10 +93,10 @@ static void usage_complete(int argc, char *argv[])
exit(-1);
}
static bool is_equal(const void *obj, const void *userp)
static bool is_equal(const void *ap, const void *bp)
{
const long *a = obj;
const long *b = userp;
const long *a = ap;
const long *b = bp;
return *a == *b;
}
@ -150,7 +150,7 @@ static void do_rw(struct thread_info *info)
p = &keys[info->r & (lookup_range - 1)];
hash = h(*p);
read = qht_lookup(&ht, is_equal, p, hash);
read = qht_lookup(&ht, p, hash);
if (read) {
stats->rd++;
} else {
@ -162,7 +162,7 @@ static void do_rw(struct thread_info *info)
if (info->write_op) {
bool written = false;
if (qht_lookup(&ht, is_equal, p, hash) == NULL) {
if (qht_lookup(&ht, p, hash) == NULL) {
written = qht_insert(&ht, p, hash);
}
if (written) {
@ -173,7 +173,7 @@ static void do_rw(struct thread_info *info)
} else {
bool removed = false;
if (qht_lookup(&ht, is_equal, p, hash)) {
if (qht_lookup(&ht, p, hash)) {
removed = qht_remove(&ht, p, hash);
}
if (removed) {
@ -308,7 +308,7 @@ static void htable_init(void)
}
/* initialize the hash table */
qht_init(&ht, qht_n_elems, qht_mode);
qht_init(&ht, is_equal, qht_n_elems, qht_mode);
assert(init_size <= init_range);
pr_params();

15
tests/test-qht.c
View File

@ -13,10 +13,10 @@
static struct qht ht;
static int32_t arr[N * 2];
static bool is_equal(const void *obj, const void *userp)
static bool is_equal(const void *ap, const void *bp)
{
const int32_t *a = obj;
const int32_t *b = userp;
const int32_t *a = ap;
const int32_t *b = bp;
return *a == *b;
}
@ -60,7 +60,12 @@ static void check(int a, int b, bool expected)
val = i;
hash = i;
p = qht_lookup(&ht, is_equal, &val, hash);
/* test both lookup variants; results should be the same */
if (i % 2) {
p = qht_lookup(&ht, &val, hash);
} else {
p = qht_lookup_custom(&ht, &val, hash, is_equal);
}
g_assert_true(!!p == expected);
}
rcu_read_unlock();
@ -102,7 +107,7 @@ static void qht_do_test(unsigned int mode, size_t init_entries)
/* under KVM we might fetch stats from an uninitialized qht */
check_n(0);
qht_init(&ht, 0, mode);
qht_init(&ht, is_equal, 0, mode);
check_n(0);
insert(0, N);

14
util/qht.c
View File

@ -351,11 +351,14 @@ static struct qht_map *qht_map_create(size_t n_buckets)
return map;
}
void qht_init(struct qht *ht, size_t n_elems, unsigned int mode)
void qht_init(struct qht *ht, qht_cmp_func_t cmp, size_t n_elems,
unsigned int mode)
{
struct qht_map *map;
size_t n_buckets = qht_elems_to_buckets(n_elems);
g_assert(cmp);
ht->cmp = cmp;
ht->mode = mode;
qemu_mutex_init(&ht->lock);
map = qht_map_create(n_buckets);
@ -479,8 +482,8 @@ void *qht_lookup__slowpath(struct qht_bucket *b, qht_lookup_func_t func,
return ret;
}
void *qht_lookup(struct qht *ht, qht_lookup_func_t func, const void *userp,
uint32_t hash)
void *qht_lookup_custom(struct qht *ht, const void *userp, uint32_t hash,
qht_lookup_func_t func)
{
struct qht_bucket *b;
struct qht_map *map;
@ -502,6 +505,11 @@ void *qht_lookup(struct qht *ht, qht_lookup_func_t func, const void *userp,
return qht_lookup__slowpath(b, func, userp, hash);
}
void *qht_lookup(struct qht *ht, const void *userp, uint32_t hash)
{
return qht_lookup_custom(ht, userp, hash, ht->cmp);
}
/* 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,