From: Stefano Garzarella <sgarzare@redhat.com>
To: qemu-devel@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>,
qemu-block@nongnu.org, Markus Armbruster <armbru@redhat.com>,
Hanna Reitz <hreitz@redhat.com>,
Stefan Hajnoczi <stefanha@redhat.com>,
Eric Blake <eblake@redhat.com>
Subject: [PATCH v2 2/3] linux-aio: add `dev_max_batch` parameter to laio_co_submit()
Date: Tue, 26 Oct 2021 18:23:45 +0200 [thread overview]
Message-ID: <20211026162346.253081-3-sgarzare@redhat.com> (raw)
In-Reply-To: <20211026162346.253081-1-sgarzare@redhat.com>
This new parameter can be used by block devices to limit the
Linux AIO batch size more than the limit set by the AIO context.
file-posix backend supports this, passing its `aio-max-batch` option
previously added.
Add an helper function to calculate the maximum batch size.
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
---
include/block/raw-aio.h | 3 ++-
block/file-posix.c | 3 ++-
block/linux-aio.c | 30 ++++++++++++++++++++++--------
3 files changed, 26 insertions(+), 10 deletions(-)
diff --git a/include/block/raw-aio.h b/include/block/raw-aio.h
index 251b10d273..ebd042fa27 100644
--- a/include/block/raw-aio.h
+++ b/include/block/raw-aio.h
@@ -51,7 +51,8 @@ typedef struct LinuxAioState LinuxAioState;
LinuxAioState *laio_init(Error **errp);
void laio_cleanup(LinuxAioState *s);
int coroutine_fn laio_co_submit(BlockDriverState *bs, LinuxAioState *s, int fd,
- uint64_t offset, QEMUIOVector *qiov, int type);
+ uint64_t offset, QEMUIOVector *qiov, int type,
+ uint64_t dev_max_batch);
void laio_detach_aio_context(LinuxAioState *s, AioContext *old_context);
void laio_attach_aio_context(LinuxAioState *s, AioContext *new_context);
void laio_io_plug(BlockDriverState *bs, LinuxAioState *s);
diff --git a/block/file-posix.c b/block/file-posix.c
index d655fd0c45..baf4197e88 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -2066,7 +2066,8 @@ static int coroutine_fn raw_co_prw(BlockDriverState *bs, uint64_t offset,
} else if (s->use_linux_aio) {
LinuxAioState *aio = aio_get_linux_aio(bdrv_get_aio_context(bs));
assert(qiov->size == bytes);
- return laio_co_submit(bs, aio, s->fd, offset, qiov, type);
+ return laio_co_submit(bs, aio, s->fd, offset, qiov, type,
+ s->aio_max_batch);
#endif
}
diff --git a/block/linux-aio.c b/block/linux-aio.c
index 0dab507b71..88b44fee72 100644
--- a/block/linux-aio.c
+++ b/block/linux-aio.c
@@ -334,6 +334,23 @@ static void ioq_submit(LinuxAioState *s)
}
}
+static uint64_t laio_max_batch(LinuxAioState *s, uint64_t dev_max_batch)
+{
+ uint64_t max_batch = s->aio_context->aio_max_batch ?: DEFAULT_MAX_BATCH;
+
+ /*
+ * AIO context can be shared between multiple block devices, so
+ * `dev_max_batch` allows reducing the batch size for latency-sensitive
+ * devices.
+ */
+ max_batch = MIN_NON_ZERO(dev_max_batch, max_batch);
+
+ /* limit the batch with the number of available events */
+ max_batch = MIN_NON_ZERO(MAX_EVENTS - s->io_q.in_flight, max_batch);
+
+ return max_batch;
+}
+
void laio_io_plug(BlockDriverState *bs, LinuxAioState *s)
{
s->io_q.plugged++;
@@ -349,15 +366,11 @@ void laio_io_unplug(BlockDriverState *bs, LinuxAioState *s)
}
static int laio_do_submit(int fd, struct qemu_laiocb *laiocb, off_t offset,
- int type)
+ int type, uint64_t dev_max_batch)
{
LinuxAioState *s = laiocb->ctx;
struct iocb *iocbs = &laiocb->iocb;
QEMUIOVector *qiov = laiocb->qiov;
- int64_t max_batch = s->aio_context->aio_max_batch ?: DEFAULT_MAX_BATCH;
-
- /* limit the batch with the number of available events */
- max_batch = MIN_NON_ZERO(MAX_EVENTS - s->io_q.in_flight, max_batch);
switch (type) {
case QEMU_AIO_WRITE:
@@ -378,7 +391,7 @@ static int laio_do_submit(int fd, struct qemu_laiocb *laiocb, off_t offset,
s->io_q.in_queue++;
if (!s->io_q.blocked &&
(!s->io_q.plugged ||
- s->io_q.in_queue >= max_batch)) {
+ s->io_q.in_queue >= laio_max_batch(s, dev_max_batch))) {
ioq_submit(s);
}
@@ -386,7 +399,8 @@ static int laio_do_submit(int fd, struct qemu_laiocb *laiocb, off_t offset,
}
int coroutine_fn laio_co_submit(BlockDriverState *bs, LinuxAioState *s, int fd,
- uint64_t offset, QEMUIOVector *qiov, int type)
+ uint64_t offset, QEMUIOVector *qiov, int type,
+ uint64_t dev_max_batch)
{
int ret;
struct qemu_laiocb laiocb = {
@@ -398,7 +412,7 @@ int coroutine_fn laio_co_submit(BlockDriverState *bs, LinuxAioState *s, int fd,
.qiov = qiov,
};
- ret = laio_do_submit(fd, &laiocb, offset, type);
+ ret = laio_do_submit(fd, &laiocb, offset, type, dev_max_batch);
if (ret < 0) {
return ret;
}
--
2.31.1
next prev parent reply other threads:[~2021-10-26 16:29 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-26 16:23 [PATCH v2 0/3] linux-aio: allow block devices to limit aio-max-batch Stefano Garzarella
2021-10-26 16:23 ` [PATCH v2 1/3] file-posix: add `aio-max-batch` option Stefano Garzarella
2021-10-27 4:28 ` Markus Armbruster
2021-10-27 9:23 ` Stefano Garzarella
2021-10-27 13:06 ` Kevin Wolf
2021-10-27 14:50 ` Stefano Garzarella
2021-11-02 11:52 ` Stefano Garzarella
2021-10-27 9:07 ` Stefan Hajnoczi
2021-10-26 16:23 ` Stefano Garzarella [this message]
2021-10-26 16:23 ` [PATCH v2 3/3] linux-aio: add `dev_max_batch` parameter to laio_io_unplug() Stefano Garzarella
2021-11-02 12:07 ` [PATCH v2 0/3] linux-aio: allow block devices to limit aio-max-batch Kevin Wolf
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