block/qcow2: introduce parallel subrequest handling in read and write
It improves performance for fragmented qcow2 images.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20190916175324.18478-6-vsementsov@virtuozzo.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
diff --git a/block/qcow2.c b/block/qcow2.c
index 164b22e..7961c05 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -41,6 +41,7 @@
#include "qapi/qobject-input-visitor.h"
#include "qapi/qapi-visit-block-core.h"
#include "crypto.h"
+#include "block/aio_task.h"
/*
Differences with QCOW:
@@ -2025,6 +2026,60 @@
return ret;
}
+typedef struct Qcow2AioTask {
+ AioTask task;
+
+ BlockDriverState *bs;
+ QCow2ClusterType cluster_type; /* only for read */
+ uint64_t file_cluster_offset;
+ uint64_t offset;
+ uint64_t bytes;
+ QEMUIOVector *qiov;
+ uint64_t qiov_offset;
+ QCowL2Meta *l2meta; /* only for write */
+} Qcow2AioTask;
+
+static coroutine_fn int qcow2_co_preadv_task_entry(AioTask *task);
+static coroutine_fn int qcow2_add_task(BlockDriverState *bs,
+ AioTaskPool *pool,
+ AioTaskFunc func,
+ QCow2ClusterType cluster_type,
+ uint64_t file_cluster_offset,
+ uint64_t offset,
+ uint64_t bytes,
+ QEMUIOVector *qiov,
+ size_t qiov_offset,
+ QCowL2Meta *l2meta)
+{
+ Qcow2AioTask local_task;
+ Qcow2AioTask *task = pool ? g_new(Qcow2AioTask, 1) : &local_task;
+
+ *task = (Qcow2AioTask) {
+ .task.func = func,
+ .bs = bs,
+ .cluster_type = cluster_type,
+ .qiov = qiov,
+ .file_cluster_offset = file_cluster_offset,
+ .offset = offset,
+ .bytes = bytes,
+ .qiov_offset = qiov_offset,
+ .l2meta = l2meta,
+ };
+
+ trace_qcow2_add_task(qemu_coroutine_self(), bs, pool,
+ func == qcow2_co_preadv_task_entry ? "read" : "write",
+ cluster_type, file_cluster_offset, offset, bytes,
+ qiov, qiov_offset);
+
+ if (!pool) {
+ return func(&task->task);
+ }
+
+ aio_task_pool_start_task(pool, &task->task);
+
+ return 0;
+}
+
static coroutine_fn int qcow2_co_preadv_task(BlockDriverState *bs,
QCow2ClusterType cluster_type,
uint64_t file_cluster_offset,
@@ -2074,18 +2129,28 @@
g_assert_not_reached();
}
+static coroutine_fn int qcow2_co_preadv_task_entry(AioTask *task)
+{
+ Qcow2AioTask *t = container_of(task, Qcow2AioTask, task);
+
+ assert(!t->l2meta);
+
+ return qcow2_co_preadv_task(t->bs, t->cluster_type, t->file_cluster_offset,
+ t->offset, t->bytes, t->qiov, t->qiov_offset);
+}
+
static coroutine_fn int qcow2_co_preadv_part(BlockDriverState *bs,
uint64_t offset, uint64_t bytes,
QEMUIOVector *qiov,
size_t qiov_offset, int flags)
{
BDRVQcow2State *s = bs->opaque;
- int ret;
+ int ret = 0;
unsigned int cur_bytes; /* number of bytes in current iteration */
uint64_t cluster_offset = 0;
+ AioTaskPool *aio = NULL;
- while (bytes != 0) {
-
+ while (bytes != 0 && aio_task_pool_status(aio) == 0) {
/* prepare next request */
cur_bytes = MIN(bytes, INT_MAX);
if (s->crypto) {
@@ -2097,7 +2162,7 @@
ret = qcow2_get_cluster_offset(bs, offset, &cur_bytes, &cluster_offset);
qemu_co_mutex_unlock(&s->lock);
if (ret < 0) {
- return ret;
+ goto out;
}
if (ret == QCOW2_CLUSTER_ZERO_PLAIN ||
@@ -2106,11 +2171,14 @@
{
qemu_iovec_memset(qiov, qiov_offset, 0, cur_bytes);
} else {
- ret = qcow2_co_preadv_task(bs, ret,
- cluster_offset, offset, cur_bytes,
- qiov, qiov_offset);
+ if (!aio && cur_bytes != bytes) {
+ aio = aio_task_pool_new(QCOW2_MAX_WORKERS);
+ }
+ ret = qcow2_add_task(bs, aio, qcow2_co_preadv_task_entry, ret,
+ cluster_offset, offset, cur_bytes,
+ qiov, qiov_offset, NULL);
if (ret < 0) {
- return ret;
+ goto out;
}
}
@@ -2119,7 +2187,16 @@
qiov_offset += cur_bytes;
}
- return 0;
+out:
+ if (aio) {
+ aio_task_pool_wait_all(aio);
+ if (ret == 0) {
+ ret = aio_task_pool_status(aio);
+ }
+ g_free(aio);
+ }
+
+ return ret;
}
/* Check if it's possible to merge a write request with the writing of
@@ -2324,6 +2401,17 @@
return ret;
}
+static coroutine_fn int qcow2_co_pwritev_task_entry(AioTask *task)
+{
+ Qcow2AioTask *t = container_of(task, Qcow2AioTask, task);
+
+ assert(!t->cluster_type);
+
+ return qcow2_co_pwritev_task(t->bs, t->file_cluster_offset,
+ t->offset, t->bytes, t->qiov, t->qiov_offset,
+ t->l2meta);
+}
+
static coroutine_fn int qcow2_co_pwritev_part(
BlockDriverState *bs, uint64_t offset, uint64_t bytes,
QEMUIOVector *qiov, size_t qiov_offset, int flags)
@@ -2334,10 +2422,11 @@
unsigned int cur_bytes; /* number of sectors in current iteration */
uint64_t cluster_offset;
QCowL2Meta *l2meta = NULL;
+ AioTaskPool *aio = NULL;
trace_qcow2_writev_start_req(qemu_coroutine_self(), offset, bytes);
- while (bytes != 0) {
+ while (bytes != 0 && aio_task_pool_status(aio) == 0) {
l2meta = NULL;
@@ -2369,8 +2458,12 @@
qemu_co_mutex_unlock(&s->lock);
- ret = qcow2_co_pwritev_task(bs, cluster_offset, offset, cur_bytes,
- qiov, qiov_offset, l2meta);
+ if (!aio && cur_bytes != bytes) {
+ aio = aio_task_pool_new(QCOW2_MAX_WORKERS);
+ }
+ ret = qcow2_add_task(bs, aio, qcow2_co_pwritev_task_entry, 0,
+ cluster_offset, offset, cur_bytes,
+ qiov, qiov_offset, l2meta);
l2meta = NULL; /* l2meta is consumed by qcow2_co_pwritev_task() */
if (ret < 0) {
goto fail_nometa;
@@ -2391,6 +2484,14 @@
qemu_co_mutex_unlock(&s->lock);
fail_nometa:
+ if (aio) {
+ aio_task_pool_wait_all(aio);
+ if (ret == 0) {
+ ret = aio_task_pool_status(aio);
+ }
+ g_free(aio);
+ }
+
trace_qcow2_writev_done_req(qemu_coroutine_self(), ret);
return ret;
diff --git a/block/qcow2.h b/block/qcow2.h
index a488d76..f51f478 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -65,6 +65,9 @@
#define QCOW2_MAX_BITMAPS 65535
#define QCOW2_MAX_BITMAP_DIRECTORY_SIZE (1024 * QCOW2_MAX_BITMAPS)
+/* Maximum of parallel sub-request per guest request */
+#define QCOW2_MAX_WORKERS 8
+
/* indicate that the refcount of the referenced cluster is exactly one. */
#define QCOW_OFLAG_COPIED (1ULL << 63)
/* indicate that the cluster is compressed (they never have the copied flag) */
diff --git a/block/trace-events b/block/trace-events
index 04209f0..3aa27e6 100644
--- a/block/trace-events
+++ b/block/trace-events
@@ -62,6 +62,7 @@
file_copy_file_range(void *bs, int src, int64_t src_off, int dst, int64_t dst_off, int64_t bytes, int flags, int64_t ret) "bs %p src_fd %d offset %"PRIu64" dst_fd %d offset %"PRIu64" bytes %"PRIu64" flags %d ret %"PRId64
# qcow2.c
+qcow2_add_task(void *co, void *bs, void *pool, const char *action, int cluster_type, uint64_t file_cluster_offset, uint64_t offset, uint64_t bytes, void *qiov, size_t qiov_offset) "co %p bs %p pool %p: %s: cluster_type %d file_cluster_offset %" PRIu64 " offset %" PRIu64 " bytes %" PRIu64 " qiov %p qiov_offset %zu"
qcow2_writev_start_req(void *co, int64_t offset, int bytes) "co %p offset 0x%" PRIx64 " bytes %d"
qcow2_writev_done_req(void *co, int ret) "co %p ret %d"
qcow2_writev_start_part(void *co) "co %p"
