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[Qemu-devel] [PATCH v6 2/3] linux-aio: handling -EAGAIN for !s->io_q.plu
From: |
Ming Lei |
Subject: |
[Qemu-devel] [PATCH v6 2/3] linux-aio: handling -EAGAIN for !s->io_q.plugged case |
Date: |
Tue, 25 Nov 2014 15:23:12 +0800 |
Previously -EAGAIN is simply ignored for !s->io_q.plugged case,
and sometimes it is easy to cause -EIO to VM, such as NVME device.
This patch handles -EAGAIN by io queue for !s->io_q.plugged case,
and it will be retried in following aio completion cb.
Reviewed-by: Paolo Bonzini <address@hidden>
Suggested-by: Paolo Bonzini <address@hidden>
Signed-off-by: Ming Lei <address@hidden>
---
block/linux-aio.c | 24 ++++++++++++++++--------
1 file changed, 16 insertions(+), 8 deletions(-)
diff --git a/block/linux-aio.c b/block/linux-aio.c
index 11ac828..ac25722 100644
--- a/block/linux-aio.c
+++ b/block/linux-aio.c
@@ -282,8 +282,13 @@ static int ioq_enqueue(struct qemu_laio_state *s, struct
iocb *iocb)
s->io_q.iocbs[idx++] = iocb;
s->io_q.idx = idx;
- /* submit immediately if queue depth is above 2/3 */
- if (idx > s->io_q.size * 2 / 3) {
+ /*
+ * This is reached in two cases: queue not plugged but io_submit
+ * returned -EAGAIN, or queue plugged. In the latter case, start
+ * submitting some I/O if the queue is getting too full. In the
+ * former case, instead, wait until an I/O operation is completed.
+ */
+ if (s->io_q.plugged && unlikely(idx > s->io_q.size * 2 / 3)) {
ioq_submit(s);
}
@@ -348,15 +353,18 @@ BlockAIOCB *laio_submit(BlockDriverState *bs, void
*aio_ctx, int fd,
}
io_set_eventfd(&laiocb->iocb, event_notifier_get_fd(&s->e));
- if (!s->io_q.plugged) {
- if (io_submit(s->ctx, 1, &iocbs) < 0) {
- goto out_free_aiocb;
- }
- } else {
- if (ioq_enqueue(s, iocbs) < 0) {
+ /* Switch to queue mode until -EAGAIN is handled */
+ if (!s->io_q.plugged && !s->io_q.idx) {
+ int ret = io_submit(s->ctx, 1, &iocbs);
+ if (ret >= 0) {
+ return &laiocb->common;
+ } else if (ret != -EAGAIN) {
goto out_free_aiocb;
}
}
+ if (ioq_enqueue(s, iocbs) < 0) {
+ goto out_free_aiocb;
+ }
return &laiocb->common;
out_free_aiocb:
--
1.7.9.5
- Re: [Qemu-devel] [PATCH v6 1/3] linux-aio: fix submit aio as a batch, (continued)
- Re: [Qemu-devel] [PATCH v6 1/3] linux-aio: fix submit aio as a batch, Stefan Hajnoczi, 2014/11/25
- Re: [Qemu-devel] [PATCH v6 1/3] linux-aio: fix submit aio as a batch, Ming Lei, 2014/11/25
- Re: [Qemu-devel] [PATCH v6 1/3] linux-aio: fix submit aio as a batch, Stefan Hajnoczi, 2014/11/25
- Re: [Qemu-devel] [PATCH v6 1/3] linux-aio: fix submit aio as a batch, Ming Lei, 2014/11/26
- Re: [Qemu-devel] [PATCH v6 1/3] linux-aio: fix submit aio as a batch, Stefan Hajnoczi, 2014/11/27
- Re: [Qemu-devel] [PATCH v6 1/3] linux-aio: fix submit aio as a batch, Paolo Bonzini, 2014/11/27
- Re: [Qemu-devel] [PATCH v6 1/3] linux-aio: fix submit aio as a batch, Ming Lei, 2014/11/27
Re: [Qemu-devel] [PATCH v6 1/3] linux-aio: fix submit aio as a batch, Kevin Wolf, 2014/11/26
Re: [Qemu-devel] [PATCH v6 1/3] linux-aio: fix submit aio as a batch, Kevin Wolf, 2014/11/26
[Qemu-devel] [PATCH v6 2/3] linux-aio: handling -EAGAIN for !s->io_q.plugged case,
Ming Lei <=
[Qemu-devel] [PATCH v6 3/3] linux-aio: remove 'node' from 'struct qemu_laiocb', Ming Lei, 2014/11/25