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block: throttle-groups: Use BlockBackend pointers internally 

As a first step towards moving I/O throttling to the BlockBackend level,
this patch changes all pointers in struct ThrottleGroup from referencing
a BlockDriverState to referencing a BlockBackend.

This change is valid because we made sure that throttling can only be
enabled on BDSes which have a BB attached.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Kevin Wolf 2016-03-21 11:30:57 +01:00
parent f2cd875d54
commit 31dce3ccca
6 changed files with 83 additions and 78 deletions
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4
block/io.c
View File

@ -70,7 +70,7 @@ void bdrv_io_limits_disable(BlockDriverState *bs)
{
assert(bs->throttle_state);
bdrv_no_throttling_begin(bs);
throttle_group_unregister_bs(bs);
throttle_group_unregister_blk(bs->blk);
bdrv_no_throttling_end(bs);
}
@ -78,7 +78,7 @@ void bdrv_io_limits_disable(BlockDriverState *bs)
void bdrv_io_limits_enable(BlockDriverState *bs, const char *group)
{
assert(!bs->throttle_state);
throttle_group_register_bs(bs, group);
throttle_group_register_blk(bs->blk, group);
}
void bdrv_io_limits_update_group(BlockDriverState *bs, const char *group)

134
block/throttle-groups.c
View File

@ -23,6 +23,7 @@
*/
#include "qemu/osdep.h"
#include "sysemu/block-backend.h"
#include "block/throttle-groups.h"
#include "qemu/queue.h"
#include "qemu/thread.h"
@ -57,8 +58,8 @@ typedef struct ThrottleGroup {
QemuMutex lock; /* This lock protects the following four fields */
ThrottleState ts;
QLIST_HEAD(, BlockDriverState) head;
BlockDriverState *tokens[2];
QLIST_HEAD(, BlockBackendPublic) head;
BlockBackend *tokens[2];
bool any_timer_armed[2];
/* These two are protected by the global throttle_groups_lock */
@ -145,81 +146,81 @@ const char *throttle_group_get_name(BlockDriverState *bs)
return tg->name;
}
/* Return the next BlockDriverState in the round-robin sequence,
* simulating a circular list.
/* Return the next BlockBackend in the round-robin sequence, simulating a
* circular list.
*
* This assumes that tg->lock is held.
*
* @bs: the current BlockDriverState
* @ret: the next BlockDriverState in the sequence
* @blk: the current BlockBackend
* @ret: the next BlockBackend in the sequence
*/
static BlockDriverState *throttle_group_next_bs(BlockDriverState *bs)
static BlockBackend *throttle_group_next_blk(BlockBackend *blk)
{
BlockDriverState *bs = blk_bs(blk);
ThrottleState *ts = bs->throttle_state;
ThrottleGroup *tg = container_of(ts, ThrottleGroup, ts);
BlockDriverState *next = QLIST_NEXT(bs, round_robin);
BlockBackendPublic *next = QLIST_NEXT(blk_get_public(blk), round_robin);
if (!next) {
return QLIST_FIRST(&tg->head);
next = QLIST_FIRST(&tg->head);
}
return next;
return blk_by_public(next);
}
/* Return the next BlockDriverState in the round-robin sequence with
* pending I/O requests.
/* Return the next BlockBackend in the round-robin sequence with pending I/O
* requests.
*
* This assumes that tg->lock is held.
*
* @bs: the current BlockDriverState
* @blk: the current BlockBackend
* @is_write: the type of operation (read/write)
* @ret: the next BlockDriverState with pending requests, or bs
* if there is none.
* @ret: the next BlockBackend with pending requests, or blk if there is
* none.
*/
static BlockDriverState *next_throttle_token(BlockDriverState *bs,
bool is_write)
static BlockBackend *next_throttle_token(BlockBackend *blk, bool is_write)
{
ThrottleGroup *tg = container_of(bs->throttle_state, ThrottleGroup, ts);
BlockDriverState *token, *start;
ThrottleGroup *tg = container_of(blk_bs(blk)->throttle_state,
ThrottleGroup, ts);
BlockBackend *token, *start;
start = token = tg->tokens[is_write];
/* get next bs round in round robin style */
token = throttle_group_next_bs(token);
while (token != start && !token->pending_reqs[is_write]) {
token = throttle_group_next_bs(token);
token = throttle_group_next_blk(token);
while (token != start && !blk_bs(token)->pending_reqs[is_write]) {
token = throttle_group_next_blk(token);
}
/* If no IO are queued for scheduling on the next round robin token
* then decide the token is the current bs because chances are
* the current bs get the current request queued.
*/
if (token == start && !token->pending_reqs[is_write]) {
token = bs;
if (token == start && !blk_bs(token)->pending_reqs[is_write]) {
token = blk;
}
return token;
}
/* Check if the next I/O request for a BlockDriverState needs to be
* throttled or not. If there's no timer set in this group, set one
* and update the token accordingly.
/* Check if the next I/O request for a BlockBackend needs to be throttled or
* not. If there's no timer set in this group, set one and update the token
* accordingly.
*
* This assumes that tg->lock is held.
*
* @bs: the current BlockDriverState
* @blk: the current BlockBackend
* @is_write: the type of operation (read/write)
* @ret: whether the I/O request needs to be throttled or not
*/
static bool throttle_group_schedule_timer(BlockDriverState *bs,
bool is_write)
static bool throttle_group_schedule_timer(BlockBackend *blk, bool is_write)
{
ThrottleState *ts = bs->throttle_state;
ThrottleTimers *tt = &bs->throttle_timers;
ThrottleState *ts = blk_bs(blk)->throttle_state;
ThrottleTimers *tt = &blk_bs(blk)->throttle_timers;
ThrottleGroup *tg = container_of(ts, ThrottleGroup, ts);
bool must_wait;
if (bs->io_limits_disabled) {
if (blk_bs(blk)->io_limits_disabled) {
return false;
}
@ -230,9 +231,9 @@ static bool throttle_group_schedule_timer(BlockDriverState *bs,
must_wait = throttle_schedule_timer(ts, tt, is_write);
/* If a timer just got armed, set bs as the current token */
/* If a timer just got armed, set blk as the current token */
if (must_wait) {
tg->tokens[is_write] = bs;
tg->tokens[is_write] = blk;
tg->any_timer_armed[is_write] = true;
}
@ -243,18 +244,19 @@ static bool throttle_group_schedule_timer(BlockDriverState *bs,
*
* This assumes that tg->lock is held.
*
* @bs: the current BlockDriverState
* @blk: the current BlockBackend
* @is_write: the type of operation (read/write)
*/
static void schedule_next_request(BlockDriverState *bs, bool is_write)
static void schedule_next_request(BlockBackend *blk, bool is_write)
{
BlockDriverState *bs = blk_bs(blk);
ThrottleGroup *tg = container_of(bs->throttle_state, ThrottleGroup, ts);
bool must_wait;
BlockDriverState *token;
BlockBackend *token;
/* Check if there's any pending request to schedule next */
token = next_throttle_token(bs, is_write);
if (!token->pending_reqs[is_write]) {
token = next_throttle_token(blk, is_write);
if (!blk_bs(token)->pending_reqs[is_write]) {
return;
}
@ -266,9 +268,9 @@ static void schedule_next_request(BlockDriverState *bs, bool is_write)
/* Give preference to requests from the current bs */
if (qemu_in_coroutine() &&
qemu_co_queue_next(&bs->throttled_reqs[is_write])) {
token = bs;
token = blk;
} else {
ThrottleTimers *tt = &token->throttle_timers;
ThrottleTimers *tt = &blk_bs(token)->throttle_timers;
int64_t now = qemu_clock_get_ns(tt->clock_type);
timer_mod(tt->timers[is_write], now + 1);
tg->any_timer_armed[is_write] = true;
@ -290,13 +292,13 @@ void coroutine_fn throttle_group_co_io_limits_intercept(BlockDriverState *bs,
bool is_write)
{
bool must_wait;
BlockDriverState *token;
BlockBackend *token;
ThrottleGroup *tg = container_of(bs->throttle_state, ThrottleGroup, ts);
qemu_mutex_lock(&tg->lock);
/* First we check if this I/O has to be throttled. */
token = next_throttle_token(bs, is_write);
token = next_throttle_token(bs->blk, is_write);
must_wait = throttle_group_schedule_timer(token, is_write);
/* Wait if there's a timer set or queued requests of this type */
@ -312,7 +314,7 @@ void coroutine_fn throttle_group_co_io_limits_intercept(BlockDriverState *bs,
throttle_account(bs->throttle_state, is_write, bytes);
/* Schedule the next request */
schedule_next_request(bs, is_write);
schedule_next_request(bs->blk, is_write);
qemu_mutex_unlock(&tg->lock);
}
@ -395,7 +397,7 @@ static void timer_cb(BlockDriverState *bs, bool is_write)
* scheduling the next one */
if (empty_queue) {
qemu_mutex_lock(&tg->lock);
schedule_next_request(bs, is_write);
schedule_next_request(bs->blk, is_write);
qemu_mutex_unlock(&tg->lock);
}
}
@ -410,17 +412,17 @@ static void write_timer_cb(void *opaque)
timer_cb(opaque, true);
}
/* Register a BlockDriverState in the throttling group, also
* initializing its timers and updating its throttle_state pointer to
* point to it. If a throttling group with that name does not exist
* yet, it will be created.
/* Register a BlockBackend in the throttling group, also initializing its
* timers and updating its throttle_state pointer to point to it. If a
* throttling group with that name does not exist yet, it will be created.
*
* @bs: the BlockDriverState to insert
* @blk: the BlockBackend to insert
* @groupname: the name of the group
*/
void throttle_group_register_bs(BlockDriverState *bs, const char *groupname)
void throttle_group_register_blk(BlockBackend *blk, const char *groupname)
{
int i;
BlockDriverState *bs = blk_bs(blk);
ThrottleState *ts = throttle_group_incref(groupname);
ThrottleGroup *tg = container_of(ts, ThrottleGroup, ts);
int clock_type = QEMU_CLOCK_REALTIME;
@ -433,14 +435,14 @@ void throttle_group_register_bs(BlockDriverState *bs, const char *groupname)
bs->throttle_state = ts;
qemu_mutex_lock(&tg->lock);
/* If the ThrottleGroup is new set this BlockDriverState as the token */
/* If the ThrottleGroup is new set this BlockBackend as the token */
for (i = 0; i < 2; i++) {
if (!tg->tokens[i]) {
tg->tokens[i] = bs;
tg->tokens[i] = blk;
}
}
QLIST_INSERT_HEAD(&tg->head, bs, round_robin);
QLIST_INSERT_HEAD(&tg->head, blk_get_public(blk), round_robin);
throttle_timers_init(&bs->throttle_timers,
bdrv_get_aio_context(bs),
@ -452,19 +454,19 @@ void throttle_group_register_bs(BlockDriverState *bs, const char *groupname)
qemu_mutex_unlock(&tg->lock);
}
/* Unregister a BlockDriverState from its group, removing it from the
* list, destroying the timers and setting the throttle_state pointer
* to NULL.
/* Unregister a BlockBackend from its group, removing it from the list,
* destroying the timers and setting the throttle_state pointer to NULL.
*
* The BlockDriverState must not have pending throttled requests, so
* the caller has to drain them first.
* The BlockBackend must not have pending throttled requests, so the caller has
* to drain them first.
*
* The group will be destroyed if it's empty after this operation.
*
* @bs: the BlockDriverState to remove
* @blk: the BlockBackend to remove
*/
void throttle_group_unregister_bs(BlockDriverState *bs)
void throttle_group_unregister_blk(BlockBackend *blk)
{
BlockDriverState *bs = blk_bs(blk);
ThrottleGroup *tg = container_of(bs->throttle_state, ThrottleGroup, ts);
int i;
@ -474,10 +476,10 @@ void throttle_group_unregister_bs(BlockDriverState *bs)
qemu_mutex_lock(&tg->lock);
for (i = 0; i < 2; i++) {
if (tg->tokens[i] == bs) {
BlockDriverState *token = throttle_group_next_bs(bs);
if (tg->tokens[i] == blk) {
BlockBackend *token = throttle_group_next_blk(blk);
/* Take care of the case where this is the last bs in the group */
if (token == bs) {
if (token == blk) {
token = NULL;
}
tg->tokens[i] = token;
@ -485,7 +487,7 @@ void throttle_group_unregister_bs(BlockDriverState *bs)
}
/* remove the current bs from the list */
QLIST_REMOVE(bs, round_robin);
QLIST_REMOVE(blk_get_public(blk), round_robin);
throttle_timers_destroy(&bs->throttle_timers);
qemu_mutex_unlock(&tg->lock);

1
include/block/block_int.h
View File

@ -435,7 +435,6 @@ struct BlockDriverState {
ThrottleState *throttle_state;
ThrottleTimers throttle_timers;
unsigned pending_reqs[2];
QLIST_ENTRY(BlockDriverState) round_robin;
/* Offset after the highest byte written to */
uint64_t wr_highest_offset;

4
include/block/throttle-groups.h
View File

@ -36,8 +36,8 @@ void throttle_group_unref(ThrottleState *ts);
void throttle_group_config(BlockDriverState *bs, ThrottleConfig *cfg);
void throttle_group_get_config(BlockDriverState *bs, ThrottleConfig *cfg);
void throttle_group_register_bs(BlockDriverState *bs, const char *groupname);
void throttle_group_unregister_bs(BlockDriverState *bs);
void throttle_group_register_blk(BlockBackend *blk, const char *groupname);
void throttle_group_unregister_blk(BlockBackend *blk);
void throttle_group_restart_bs(BlockDriverState *bs);
void coroutine_fn throttle_group_co_io_limits_intercept(BlockDriverState *bs,

5
include/sysemu/block-backend.h
View File

@ -63,7 +63,10 @@ typedef struct BlockDevOps {
* fields that must be public. This is in particular for QLIST_ENTRY() and
* friends so that BlockBackends can be kept in lists outside block-backend.c */
typedef struct BlockBackendPublic {
int dummy; /* empty structs are illegal */
/* I/O throttling */
/* The following fields are protected by the ThrottleGroup lock.
* See the ThrottleGroup documentation for details. */
QLIST_ENTRY(BlockBackendPublic) round_robin;
} BlockBackendPublic;
BlockBackend *blk_new(Error **errp);

13
tests/test-throttle.c
View File

@ -20,6 +20,7 @@
#include "qemu/throttle.h"
#include "qemu/error-report.h"
#include "block/throttle-groups.h"
#include "sysemu/block-backend.h"
static AioContext *ctx;
static LeakyBucket bkt;
@ -589,9 +590,9 @@ static void test_groups(void)
g_assert(bdrv2->throttle_state == NULL);
g_assert(bdrv3->throttle_state == NULL);
throttle_group_register_bs(bdrv1, "bar");
throttle_group_register_bs(bdrv2, "foo");
throttle_group_register_bs(bdrv3, "bar");
throttle_group_register_blk(blk1, "bar");
throttle_group_register_blk(blk2, "foo");
throttle_group_register_blk(blk3, "bar");
g_assert(bdrv1->throttle_state != NULL);
g_assert(bdrv2->throttle_state != NULL);
@ -623,9 +624,9 @@ static void test_groups(void)
throttle_group_get_config(bdrv3, &cfg2);
g_assert(!memcmp(&cfg1, &cfg2, sizeof(cfg1)));
throttle_group_unregister_bs(bdrv1);
throttle_group_unregister_bs(bdrv2);
throttle_group_unregister_bs(bdrv3);
throttle_group_unregister_blk(blk1);
throttle_group_unregister_blk(blk2);
throttle_group_unregister_blk(blk3);
g_assert(bdrv1->throttle_state == NULL);
g_assert(bdrv2->throttle_state == NULL);