We are going to directly use one async block-copy operation for backup job, so we need rate limiter.
We want to maintain current backup behavior: only background copying is limited and copy-before-write operations only participate in limit calculation. Therefore we need one rate limiter for block-copy state and boolean flag for block-copy call state for actual limitation. Note, that we can't just calculate each chunk in limiter after successful copying: it will not save us from starting a lot of async sub-requests which will exceed limit too much. Instead let's use the following scheme on sub-request creation: 1. If at the moment limit is not exceeded, create the request and account it immediately. 2. If at the moment limit is already exceeded, drop create sub-request and handle limit instead (by sleep). With this approach we'll never exceed the limit more than by one sub-request (which pretty much matches current backup behavior). Note also, that if there is in-flight block-copy async call, block_copy_kick() should be used after set-speed to apply new setup faster. For that block_copy_kick() published in this patch. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com> Reviewed-by: Max Reitz <mre...@redhat.com> --- include/block/block-copy.h | 5 ++++- block/backup-top.c | 2 +- block/backup.c | 2 +- block/block-copy.c | 46 +++++++++++++++++++++++++++++++++++++- 4 files changed, 51 insertions(+), 4 deletions(-) diff --git a/include/block/block-copy.h b/include/block/block-copy.h index 22372aa375..b5a53ad59e 100644 --- a/include/block/block-copy.h +++ b/include/block/block-copy.h @@ -41,7 +41,7 @@ int64_t block_copy_reset_unallocated(BlockCopyState *s, int64_t offset, int64_t *count); int coroutine_fn block_copy(BlockCopyState *s, int64_t offset, int64_t bytes, - bool *error_is_read); + bool ignore_ratelimit, bool *error_is_read); /* * Run block-copy in a coroutine, create corresponding BlockCopyCallState @@ -76,6 +76,9 @@ bool block_copy_call_succeeded(BlockCopyCallState *call_state); bool block_copy_call_failed(BlockCopyCallState *call_state); int block_copy_call_status(BlockCopyCallState *call_state, bool *error_is_read); +void block_copy_set_speed(BlockCopyState *s, uint64_t speed); +void block_copy_kick(BlockCopyCallState *call_state); + BdrvDirtyBitmap *block_copy_dirty_bitmap(BlockCopyState *s); void block_copy_set_skip_unallocated(BlockCopyState *s, bool skip); diff --git a/block/backup-top.c b/block/backup-top.c index 789acf6965..779956ddc2 100644 --- a/block/backup-top.c +++ b/block/backup-top.c @@ -61,7 +61,7 @@ static coroutine_fn int backup_top_cbw(BlockDriverState *bs, uint64_t offset, off = QEMU_ALIGN_DOWN(offset, s->cluster_size); end = QEMU_ALIGN_UP(offset + bytes, s->cluster_size); - return block_copy(s->bcs, off, end - off, NULL); + return block_copy(s->bcs, off, end - off, true, NULL); } static int coroutine_fn backup_top_co_pdiscard(BlockDriverState *bs, diff --git a/block/backup.c b/block/backup.c index 4b07e9115d..09ff5a92ef 100644 --- a/block/backup.c +++ b/block/backup.c @@ -72,7 +72,7 @@ static int coroutine_fn backup_do_cow(BackupBlockJob *job, trace_backup_do_cow_enter(job, start, offset, bytes); - ret = block_copy(job->bcs, start, end - start, error_is_read); + ret = block_copy(job->bcs, start, end - start, true, error_is_read); trace_backup_do_cow_return(job, offset, bytes, ret); diff --git a/block/block-copy.c b/block/block-copy.c index 6bf1735b93..fa27450b14 100644 --- a/block/block-copy.c +++ b/block/block-copy.c @@ -26,6 +26,7 @@ #define BLOCK_COPY_MAX_BUFFER (1 * MiB) #define BLOCK_COPY_MAX_MEM (128 * MiB) #define BLOCK_COPY_MAX_WORKERS 64 +#define BLOCK_COPY_SLICE_TIME 100000000ULL /* ns */ static coroutine_fn int block_copy_task_entry(AioTask *task); @@ -36,6 +37,7 @@ typedef struct BlockCopyCallState { int64_t bytes; int max_workers; int64_t max_chunk; + bool ignore_ratelimit; BlockCopyAsyncCallbackFunc cb; void *cb_opaque; @@ -48,6 +50,7 @@ typedef struct BlockCopyCallState { /* State */ int ret; bool finished; + QemuCoSleepState *sleep_state; /* OUT parameters */ bool error_is_read; @@ -111,6 +114,9 @@ typedef struct BlockCopyState { void *progress_opaque; SharedResource *mem; + + uint64_t speed; + RateLimit rate_limit; } BlockCopyState; static BlockCopyTask *find_conflicting_task(BlockCopyState *s, @@ -623,6 +629,21 @@ block_copy_dirty_clusters(BlockCopyCallState *call_state) } task->zeroes = ret & BDRV_BLOCK_ZERO; + if (s->speed) { + if (!call_state->ignore_ratelimit) { + uint64_t ns = ratelimit_calculate_delay(&s->rate_limit, 0); + if (ns > 0) { + block_copy_task_end(task, -EAGAIN); + g_free(task); + qemu_co_sleep_ns_wakeable(QEMU_CLOCK_REALTIME, ns, + &call_state->sleep_state); + continue; + } + } + + ratelimit_calculate_delay(&s->rate_limit, task->bytes); + } + trace_block_copy_process(s, task->offset); co_get_from_shres(s->mem, task->bytes); @@ -661,6 +682,13 @@ out: return ret < 0 ? ret : found_dirty; } +void block_copy_kick(BlockCopyCallState *call_state) +{ + if (call_state->sleep_state) { + qemu_co_sleep_wake(call_state->sleep_state); + } +} + /* * block_copy_common * @@ -707,12 +735,13 @@ static int coroutine_fn block_copy_common(BlockCopyCallState *call_state) } int coroutine_fn block_copy(BlockCopyState *s, int64_t start, int64_t bytes, - bool *error_is_read) + bool ignore_ratelimit, bool *error_is_read) { BlockCopyCallState call_state = { .s = s, .offset = start, .bytes = bytes, + .ignore_ratelimit = ignore_ratelimit, .max_workers = BLOCK_COPY_MAX_WORKERS, }; @@ -798,3 +827,18 @@ void block_copy_set_skip_unallocated(BlockCopyState *s, bool skip) { s->skip_unallocated = skip; } + +void block_copy_set_speed(BlockCopyState *s, uint64_t speed) +{ + s->speed = speed; + if (speed > 0) { + ratelimit_set_speed(&s->rate_limit, speed, BLOCK_COPY_SLICE_TIME); + } + + /* + * Note: it's good to kick all call states from here, but it should be done + * only from a coroutine, to not crash if s->calls list changed while + * entering one call. So for now, the only user of this function kicks its + * only one call_state by hand. + */ +} -- 2.29.2