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linux-aio: implement io plug, unplug and flush io queue

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This patch implements .bdrv_io_plug, .bdrv_io_unplug and
.bdrv_flush_io_queue callbacks for linux-aio Block Drivers,
so that submitting I/O as a batch can be supported on linux-aio.

[Unprocessed requests are completed with -EIO instead of a bogus ret
value.
--Stefan]

Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Ming Lei 2014-07-04 18:04:34 +08:00 • committed by Stefan Hajnoczi
parent 448ad91db4
commit 1b3abdcccf
3 changed files with 141 additions and 2 deletions
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96
block/linux-aio.c
View file

@ -25,6 +25,8 @@
*/
#define MAX_EVENTS 128
#define MAX_QUEUED_IO 128
struct qemu_laiocb {
BlockDriverAIOCB common;
struct qemu_laio_state *ctx;
@ -36,9 +38,19 @@ struct qemu_laiocb {
QLIST_ENTRY(qemu_laiocb) node;
};
typedef struct {
struct iocb *iocbs[MAX_QUEUED_IO];
int plugged;
unsigned int size;
unsigned int idx;
} LaioQueue;
struct qemu_laio_state {
io_context_t ctx;
EventNotifier e;
/* io queue for submit at batch */
LaioQueue io_q;
};
static inline ssize_t io_event_ret(struct io_event *ev)
@ -135,6 +147,79 @@ static const AIOCBInfo laio_aiocb_info = {
.cancel = laio_cancel,
};
static void ioq_init(LaioQueue *io_q)
{
io_q->size = MAX_QUEUED_IO;
io_q->idx = 0;
io_q->plugged = 0;
}
static int ioq_submit(struct qemu_laio_state *s)
{
int ret, i = 0;
int len = s->io_q.idx;
do {
ret = io_submit(s->ctx, len, s->io_q.iocbs);
} while (i++ < 3 && ret == -EAGAIN);
/* empty io queue */
s->io_q.idx = 0;
if (ret < 0) {
i = 0;
} else {
i = ret;
}
for (; i < len; i++) {
struct qemu_laiocb *laiocb =
container_of(s->io_q.iocbs[i], struct qemu_laiocb, iocb);
laiocb->ret = (ret < 0) ? ret : -EIO;
qemu_laio_process_completion(s, laiocb);
}
return ret;
}
static void ioq_enqueue(struct qemu_laio_state *s, struct iocb *iocb)
{
unsigned int idx = s->io_q.idx;
s->io_q.iocbs[idx++] = iocb;
s->io_q.idx = idx;
/* submit immediately if queue is full */
if (idx == s->io_q.size) {
ioq_submit(s);
}
}
void laio_io_plug(BlockDriverState *bs, void *aio_ctx)
{
struct qemu_laio_state *s = aio_ctx;
s->io_q.plugged++;
}
int laio_io_unplug(BlockDriverState *bs, void *aio_ctx, bool unplug)
{
struct qemu_laio_state *s = aio_ctx;
int ret = 0;
assert(s->io_q.plugged > 0 || !unplug);
if (unplug && --s->io_q.plugged > 0) {
return 0;
}
if (s->io_q.idx > 0) {
ret = ioq_submit(s);
}
return ret;
}
BlockDriverAIOCB *laio_submit(BlockDriverState *bs, void *aio_ctx, int fd,
int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
BlockDriverCompletionFunc *cb, void *opaque, int type)
@ -168,8 +253,13 @@ BlockDriverAIOCB *laio_submit(BlockDriverState *bs, void *aio_ctx, int fd,
}
io_set_eventfd(&laiocb->iocb, event_notifier_get_fd(&s->e));
if (io_submit(s->ctx, 1, &iocbs) < 0)
goto out_free_aiocb;
if (!s->io_q.plugged) {
if (io_submit(s->ctx, 1, &iocbs) < 0) {
goto out_free_aiocb;
}
} else {
ioq_enqueue(s, iocbs);
}
return &laiocb->common;
out_free_aiocb:
@ -204,6 +294,8 @@ void *laio_init(void)
goto out_close_efd;
}
ioq_init(&s->io_q);
return s;
out_close_efd: