Stop using the .bdrv_co_io_plug() API because it is not multi-queue
block layer friendly. Use the new blk_io_plug_call() API to batch I/O
submission instead.
Note that a dev_max_batch check is dropped in laio_io_unplug() because
the semantics of unplug_fn() are different from .bdrv_co_unplug():
1. unplug_fn() is only called when the last blk_io_unplug() call occurs,
not every time blk_io_unplug() is called.
2. unplug_fn() is per-thread, not per-BlockDriverState, so there is no
way to get per-BlockDriverState fields like dev_max_batch.
Therefore this condition cannot be moved to laio_unplug_fn(). It is not
obvious that this condition affects performance in practice, so I am
removing it instead of trying to come up with a more complex mechanism
to preserve the condition.
Signed-off-by: Stefan Hajnoczi <stefanha@xxxxxxxxxx>
Reviewed-by: Eric Blake <eblake@xxxxxxxxxx>
Acked-by: Kevin Wolf <kwolf@xxxxxxxxxx>
Reviewed-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>
Message-id: 20230530180959.1108766-6-stefanha@xxxxxxxxxx
Signed-off-by: Stefan Hajnoczi <stefanha@xxxxxxxxxx>
---
include/block/raw-aio.h | 7 -------
block/file-posix.c | 28 ----------------------------
block/linux-aio.c | 41 +++++++++++------------------------------
3 files changed, 11 insertions(+), 65 deletions(-)
diff --git a/include/block/raw-aio.h b/include/block/raw-aio.h
index da60ca13ef..0f63c2800c 100644
--- a/include/block/raw-aio.h
+++ b/include/block/raw-aio.h
@@ -62,13 +62,6 @@ int coroutine_fn laio_co_submit(int fd, uint64_t offset, QEMUIOVector *qiov,
void laio_detach_aio_context(LinuxAioState *s, AioContext *old_context);
void laio_attach_aio_context(LinuxAioState *s, AioContext *new_context);
-
-/*
- * laio_io_plug/unplug work in the thread's current AioContext, therefore the
- * caller must ensure that they are paired in the same IOThread.
- */
-void laio_io_plug(void);
-void laio_io_unplug(uint64_t dev_max_batch);
#endif
/* io_uring.c - Linux io_uring implementation */
#ifdef CONFIG_LINUX_IO_URING
diff --git a/block/file-posix.c b/block/file-posix.c
index 7baa8491dd..ac1ed54811 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -2550,26 +2550,6 @@ static int coroutine_fn raw_co_pwritev(BlockDriverState *bs, int64_t offset,
return raw_co_prw(bs, offset, bytes, qiov, QEMU_AIO_WRITE);
}
-static void coroutine_fn raw_co_io_plug(BlockDriverState *bs)
-{
- BDRVRawState __attribute__((unused)) *s = bs->opaque;
-#ifdef CONFIG_LINUX_AIO
- if (s->use_linux_aio) {
- laio_io_plug();
- }
-#endif
-}
-
-static void coroutine_fn raw_co_io_unplug(BlockDriverState *bs)
-{
- BDRVRawState __attribute__((unused)) *s = bs->opaque;
-#ifdef CONFIG_LINUX_AIO
- if (s->use_linux_aio) {
- laio_io_unplug(s->aio_max_batch);
- }
-#endif
-}
-
static int coroutine_fn raw_co_flush_to_disk(BlockDriverState *bs)
{
BDRVRawState *s = bs->opaque;
@@ -3914,8 +3894,6 @@ BlockDriver bdrv_file = {
.bdrv_co_copy_range_from = raw_co_copy_range_from,
.bdrv_co_copy_range_to = raw_co_copy_range_to,
.bdrv_refresh_limits = raw_refresh_limits,
- .bdrv_co_io_plug = raw_co_io_plug,
- .bdrv_co_io_unplug = raw_co_io_unplug,
.bdrv_attach_aio_context = raw_aio_attach_aio_context,
.bdrv_co_truncate = raw_co_truncate,
@@ -4286,8 +4264,6 @@ static BlockDriver bdrv_host_device = {
.bdrv_co_copy_range_from = raw_co_copy_range_from,
.bdrv_co_copy_range_to = raw_co_copy_range_to,
.bdrv_refresh_limits = raw_refresh_limits,
- .bdrv_co_io_plug = raw_co_io_plug,
- .bdrv_co_io_unplug = raw_co_io_unplug,
.bdrv_attach_aio_context = raw_aio_attach_aio_context,
.bdrv_co_truncate = raw_co_truncate,
@@ -4424,8 +4400,6 @@ static BlockDriver bdrv_host_cdrom = {
.bdrv_co_pwritev = raw_co_pwritev,
.bdrv_co_flush_to_disk = raw_co_flush_to_disk,
.bdrv_refresh_limits = cdrom_refresh_limits,
- .bdrv_co_io_plug = raw_co_io_plug,
- .bdrv_co_io_unplug = raw_co_io_unplug,
.bdrv_attach_aio_context = raw_aio_attach_aio_context,
.bdrv_co_truncate = raw_co_truncate,
@@ -4552,8 +4526,6 @@ static BlockDriver bdrv_host_cdrom = {
.bdrv_co_pwritev = raw_co_pwritev,
.bdrv_co_flush_to_disk = raw_co_flush_to_disk,
.bdrv_refresh_limits = cdrom_refresh_limits,
- .bdrv_co_io_plug = raw_co_io_plug,
- .bdrv_co_io_unplug = raw_co_io_unplug,
.bdrv_attach_aio_context = raw_aio_attach_aio_context,
.bdrv_co_truncate = raw_co_truncate,
diff --git a/block/linux-aio.c b/block/linux-aio.c
index 916f001e32..561c71a9ae 100644
--- a/block/linux-aio.c
+++ b/block/linux-aio.c
@@ -15,6 +15,7 @@
#include "qemu/event_notifier.h"
#include "qemu/coroutine.h"
#include "qapi/error.h"
+#include "sysemu/block-backend.h"
/* Only used for assertions. */
#include "qemu/coroutine_int.h"
@@ -46,7 +47,6 @@ struct qemu_laiocb {
};
typedef struct {
- int plugged;
unsigned int in_queue;
unsigned int in_flight;
bool blocked;
@@ -236,7 +236,7 @@ static void qemu_laio_process_completions_and_submit(LinuxAioState *s)
{
qemu_laio_process_completions(s);
- if (!s->io_q.plugged && !QSIMPLEQ_EMPTY(&s->io_q.pending)) {
+ if (!QSIMPLEQ_EMPTY(&s->io_q.pending)) {
ioq_submit(s);
}
}
@@ -277,7 +277,6 @@ static void qemu_laio_poll_ready(EventNotifier *opaque)
static void ioq_init(LaioQueue *io_q)
{
QSIMPLEQ_INIT(&io_q->pending);
- io_q->plugged = 0;
io_q->in_queue = 0;
io_q->in_flight = 0;
io_q->blocked = false;
@@ -354,31 +353,11 @@ static uint64_t laio_max_batch(LinuxAioState *s, uint64_t dev_max_batch)
return max_batch;
}
-void laio_io_plug(void)
+static void laio_unplug_fn(void *opaque)
{
- AioContext *ctx = qemu_get_current_aio_context();
- LinuxAioState *s = aio_get_linux_aio(ctx);
+ LinuxAioState *s = opaque;
- s->io_q.plugged++;
-}
-
-void laio_io_unplug(uint64_t dev_max_batch)
-{
- AioContext *ctx = qemu_get_current_aio_context();
- LinuxAioState *s = aio_get_linux_aio(ctx);
-
- assert(s->io_q.plugged);
- s->io_q.plugged--;
-
- /*
- * Why max batch checking is performed here:
- * Another BDS may have queued requests with a higher dev_max_batch and
- * therefore in_queue could now exceed our dev_max_batch. Re-check the max
- * batch so we can honor our device's dev_max_batch.
- */
- if (s->io_q.in_queue >= laio_max_batch(s, dev_max_batch) ||
- (!s->io_q.plugged &&
- !s->io_q.blocked && !QSIMPLEQ_EMPTY(&s->io_q.pending))) {
+ if (!s->io_q.blocked && !QSIMPLEQ_EMPTY(&s->io_q.pending)) {
ioq_submit(s);
}
}
@@ -410,10 +389,12 @@ static int laio_do_submit(int fd, struct qemu_laiocb *laiocb, off_t offset,
QSIMPLEQ_INSERT_TAIL(&s->io_q.pending, laiocb, next);
s->io_q.in_queue++;
- if (!s->io_q.blocked &&
- (!s->io_q.plugged ||
- s->io_q.in_queue >= laio_max_batch(s, dev_max_batch))) {
- ioq_submit(s);
+ if (!s->io_q.blocked) {
+ if (s->io_q.in_queue >= laio_max_batch(s, dev_max_batch)) {
+ ioq_submit(s);
+ } else {
+ blk_io_plug_call(laio_unplug_fn, s);
+ }
}
return 0;
--
2.40.1
