diff options
author | Stefan Hajnoczi <stefanha@redhat.com> | 2023-05-30 14:09:58 -0400 |
---|---|---|
committer | Stefan Hajnoczi <stefanha@redhat.com> | 2023-06-01 07:34:03 -0400 |
commit | 076682885d6fe521ed005b988fde6a67ec6818df (patch) | |
tree | 9b1e887119f0f3aff92f0fb2dccff8235bdf1730 /block/linux-aio.c | |
parent | 6a6da231b7076b8ed5409c4745e11cb14d962194 (diff) |
block/linux-aio: convert to blk_io_plug_call() API
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@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Acked-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Message-id: 20230530180959.1108766-6-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Diffstat (limited to 'block/linux-aio.c')
-rw-r--r-- | block/linux-aio.c | 41 |
1 files changed, 11 insertions, 30 deletions
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); - - 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--; + LinuxAioState *s = opaque; - /* - * 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; |