On 27/11/2019 21:08, Vladimir Sementsov-Ogievskiy wrote: > Currently, block_copy operation lock the whole requested region. But > there is no reason to lock clusters, which are already copied, it will > disturb other parallel block_copy requests for no reason. > > Let's instead do the following: > > Lock only sub-region, which we are going to operate on. Then, after > copying all dirty sub-regions, we should wait for intersecting > requests block-copy, if they failed, we should retry these new dirty > clusters. > > Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com> > --- > block/block-copy.c | 116 +++++++++++++++++++++++++++++++++++++-------- > 1 file changed, 95 insertions(+), 21 deletions(-) > > diff --git a/block/block-copy.c b/block/block-copy.c > index 20068cd699..aca44b13fb 100644 > --- a/block/block-copy.c > +++ b/block/block-copy.c > @@ -39,29 +39,62 @@ static BlockCopyInFlightReq > *block_copy_find_inflight_req(BlockCopyState *s, > return NULL; > } > > -static void coroutine_fn block_copy_wait_inflight_reqs(BlockCopyState *s, > - int64_t offset, > - int64_t bytes) > +/* > + * If there are no intersecting requests return false. Otherwise, wait for > the > + * first found intersecting request to finish and return true. > + */ > +static bool coroutine_fn block_copy_wait_one(BlockCopyState *s, int64_t > start, > + int64_t end) > { > - BlockCopyInFlightReq *req; > + BlockCopyInFlightReq *req = block_copy_find_inflight_req(s, start, end); > > - while ((req = block_copy_find_inflight_req(s, offset, bytes))) { > - qemu_co_queue_wait(&req->wait_queue, NULL); > + if (!req) { > + return false; > } > + > + qemu_co_queue_wait(&req->wait_queue, NULL); > + > + return true; > } > > +/* Called only on full-dirty region */ > static void block_copy_inflight_req_begin(BlockCopyState *s, > BlockCopyInFlightReq *req, > int64_t offset, int64_t bytes) > { > + assert(!block_copy_find_inflight_req(s, offset, bytes)); > + > + bdrv_reset_dirty_bitmap(s->copy_bitmap, offset, bytes); > + > req->offset = offset; > req->bytes = bytes; > qemu_co_queue_init(&req->wait_queue); > QLIST_INSERT_HEAD(&s->inflight_reqs, req, list); > } > > -static void coroutine_fn block_copy_inflight_req_end(BlockCopyInFlightReq > *req) > +static void coroutine_fn block_copy_inflight_req_shrink(BlockCopyState *s, > + BlockCopyInFlightReq *req, int64_t new_bytes) > { > + if (new_bytes == req->bytes) { > + return; > + } > + > + assert(new_bytes > 0 && new_bytes < req->bytes); > + > + bdrv_set_dirty_bitmap(s->copy_bitmap, > + req->offset + new_bytes, req->bytes - new_bytes); > + > + req->bytes = new_bytes; > + qemu_co_queue_restart_all(&req->wait_queue);
Won't we get the performance degradation with that function frequent call? > +} > + > +static void coroutine_fn block_copy_inflight_req_end(BlockCopyState *s, > + BlockCopyInFlightReq > *req, > + int ret) > +{ > + if (ret < 0) { > + bdrv_set_dirty_bitmap(s->copy_bitmap, req->offset, req->bytes); > + } > QLIST_REMOVE(req, list); > qemu_co_queue_restart_all(&req->wait_queue); > } > @@ -344,12 +377,19 @@ int64_t block_copy_reset_unallocated(BlockCopyState *s, > return ret; > } > > -int coroutine_fn block_copy(BlockCopyState *s, > - int64_t offset, uint64_t bytes, > - bool *error_is_read) > +/* > + * block_copy_dirty_clusters > + * > + * Copy dirty clusters in @start/@bytes range. %s/start/offset/ ? > + * Returns 1 if dirty clusters found and successfully copied, 0 if no dirty > + * clusters found and -errno on failure. > + */ > +static int coroutine_fn block_copy_dirty_clusters(BlockCopyState *s, > + int64_t offset, int64_t > bytes, > + bool *error_is_read) > { > int ret = 0; > - BlockCopyInFlightReq req; > + bool found_dirty = false; > > /* > * block_copy() user is responsible for keeping source and target in > same > @@ -361,10 +401,8 @@ int coroutine_fn block_copy(BlockCopyState *s, > assert(QEMU_IS_ALIGNED(offset, s->cluster_size)); > assert(QEMU_IS_ALIGNED(bytes, s->cluster_size)); > > - block_copy_wait_inflight_reqs(s, offset, bytes); > - block_copy_inflight_req_begin(s, &req, offset, bytes); > - > while (bytes) { > + BlockCopyInFlightReq req; > int64_t next_zero, cur_bytes, status_bytes; > > if (!bdrv_dirty_bitmap_get(s->copy_bitmap, offset)) { > @@ -374,6 +412,8 @@ int coroutine_fn block_copy(BlockCopyState *s, > continue; /* already copied */ > } > > + found_dirty = true; > + > cur_bytes = MIN(bytes, s->copy_size); > > next_zero = bdrv_dirty_bitmap_next_zero(s->copy_bitmap, offset, > @@ -383,10 +423,12 @@ int coroutine_fn block_copy(BlockCopyState *s, > assert(next_zero < offset + cur_bytes); /* no need to do MIN() > */ > cur_bytes = next_zero - offset; > } > + block_copy_inflight_req_begin(s, &req, offset, cur_bytes); > > ret = block_copy_block_status(s, offset, cur_bytes, &status_bytes); > + block_copy_inflight_req_shrink(s, &req, status_bytes); > if (s->skip_unallocated && !(ret & BDRV_BLOCK_ALLOCATED)) { > - bdrv_reset_dirty_bitmap(s->copy_bitmap, offset, status_bytes); > + block_copy_inflight_req_end(s, &req, 0); > s->progress_reset_callback(s->progress_opaque); > trace_block_copy_skip_range(s, offset, status_bytes); > offset += status_bytes; > @@ -398,15 +440,13 @@ int coroutine_fn block_copy(BlockCopyState *s, > > trace_block_copy_process(s, offset); > > - bdrv_reset_dirty_bitmap(s->copy_bitmap, offset, cur_bytes); > - > co_get_from_shres(s->mem, cur_bytes); > ret = block_copy_do_copy(s, offset, cur_bytes, ret & > BDRV_BLOCK_ZERO, > error_is_read); > co_put_to_shres(s->mem, cur_bytes); > + block_copy_inflight_req_end(s, &req, ret); > if (ret < 0) { > - bdrv_set_dirty_bitmap(s->copy_bitmap, offset, cur_bytes); > - break; > + return ret; > } > > s->progress_bytes_callback(cur_bytes, s->progress_opaque); > @@ -414,7 +454,41 @@ int coroutine_fn block_copy(BlockCopyState *s, > bytes -= cur_bytes; > } > > - block_copy_inflight_req_end(&req); > + return found_dirty; > +} > > - return ret; > +int coroutine_fn block_copy(BlockCopyState *s, int64_t start, uint64_t bytes, > + bool *error_is_read) > +{ > + while (true) { > + int ret = block_copy_dirty_clusters(s, start, bytes, error_is_read); > + > + if (ret < 0) { > + /* > + * IO operation failed, which means the whole block_copy request > + * failed. > + */ > + return ret; > + } > + if (ret) { > + /* > + * Something was copied, which means that there were yield points > + * and some new dirty bits may appered (due to failed parallel > + * block-copy requests). > + */ > + continue; > + } > + > + /* > + * Here ret == 0, which means that there is no dirty clusters in there is no dirty cluster in > + * requested region. > + */ > + > + if (!block_copy_wait_one(s, start, bytes)) { > + /* No dirty bits and nothing to wait: the whole request is done > */ > + break; > + } > + } > + > + return 0; > } > -- With the best regards, Andrey Shinkevich