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[Qemu-devel] [PATCH v2 2/5] linux-aio: track whether the queue is blocke
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [PATCH v2 2/5] linux-aio: track whether the queue is blocked |
Date: |
Thu, 11 Dec 2014 14:52:27 +0100 |
Avoid that unplug submits requests when io_submit reported that it
couldn't accept more; at the same time, try more io_submit calls if it
could handle the whole set of requests that were passed, so that the
"blocked" flag is reset as soon as possible.
After the previous patch, laio_submit already tried to avoid submitting
requests to a blocked queue, by comparing s->io_q.idx with "==" instead
of the more natural ">=". Switch to the simpler expression now that we
have the "blocked" flag.
Signed-off-by: Paolo Bonzini <address@hidden>
---
block/linux-aio.c | 47 +++++++++++++++++++++++++++--------------------
1 file changed, 27 insertions(+), 20 deletions(-)
diff --git a/block/linux-aio.c b/block/linux-aio.c
index b6fbfd8..b870942 100644
--- a/block/linux-aio.c
+++ b/block/linux-aio.c
@@ -41,6 +41,7 @@ struct qemu_laiocb {
typedef struct {
int plugged;
unsigned int idx;
+ bool blocked;
QSIMPLEQ_HEAD(, qemu_laiocb) pending;
} LaioQueue;
@@ -180,34 +181,39 @@ static void ioq_init(LaioQueue *io_q)
QSIMPLEQ_INIT(&io_q->pending);
io_q->plugged = 0;
io_q->idx = 0;
+ io_q->blocked = false;
}
static int ioq_submit(struct qemu_laio_state *s)
{
- int ret, i;
- int len = 0;
+ int ret, i, len;
struct qemu_laiocb *aiocb;
struct iocb *iocbs[MAX_QUEUED_IO];
- QSIMPLEQ_FOREACH(aiocb, &s->io_q.pending, next) {
- iocbs[len++] = &aiocb->iocb;
- if (len == MAX_QUEUED_IO) {
- break;
+ do {
+ len = 0;
+ QSIMPLEQ_FOREACH(aiocb, &s->io_q.pending, next) {
+ iocbs[len++] = &aiocb->iocb;
+ if (len == MAX_QUEUED_IO) {
+ break;
+ }
}
- }
- ret = io_submit(s->ctx, len, iocbs);
- if (ret == -EAGAIN) {
- ret = 0;
- }
- if (ret < 0) {
- abort();
- }
+ ret = io_submit(s->ctx, len, iocbs);
+ if (ret == -EAGAIN) {
+ ret = 0;
+ }
+ if (ret < 0) {
+ abort();
+ }
+
+ for (i = 0; i < ret; i++) {
+ s->io_q.idx--;
+ QSIMPLEQ_REMOVE_HEAD(&s->io_q.pending, next);
+ }
+ } while (ret == len && !QSIMPLEQ_EMPTY(&s->io_q.pending));
+ s->io_q.blocked = (s->io_q.idx > 0);
- for (i = 0; i < ret; i++) {
- s->io_q.idx--;
- QSIMPLEQ_REMOVE_HEAD(&s->io_q.pending, next);
- }
return ret;
}
@@ -229,7 +235,7 @@ int laio_io_unplug(BlockDriverState *bs, void *aio_ctx,
bool unplug)
return 0;
}
- if (!QSIMPLEQ_EMPTY(&s->io_q.pending)) {
+ if (!s->io_q.blocked && !QSIMPLEQ_EMPTY(&s->io_q.pending)) {
ret = ioq_submit(s);
}
@@ -271,7 +277,8 @@ BlockAIOCB *laio_submit(BlockDriverState *bs, void
*aio_ctx, int fd,
QSIMPLEQ_INSERT_TAIL(&s->io_q.pending, laiocb, next);
s->io_q.idx++;
- if (s->io_q.idx == (s->io_q.plugged ? MAX_QUEUED_IO : 1)) {
+ if (!s->io_q.blocked &&
+ (!s->io_q.plugged || s->io_q.idx >= MAX_QUEUED_IO)) {
ioq_submit(s);
}
return &laiocb->common;
--
2.1.0
- [Qemu-devel] [PATCH v2 0/5] linux-aio: rewrite and simplify queuing code, Paolo Bonzini, 2014/12/11
- [Qemu-devel] [PATCH v2 1/5] linux-aio: queue requests that cannot be submitted, Paolo Bonzini, 2014/12/11
- Re: [Qemu-devel] [PATCH v2 1/5] linux-aio: queue requests that cannot be submitted, Kevin Wolf, 2014/12/16
- Re: [Qemu-devel] [PATCH v2 1/5] linux-aio: queue requests that cannot be submitted, Paolo Bonzini, 2014/12/16
- Re: [Qemu-devel] [PATCH v2 1/5] linux-aio: queue requests that cannot be submitted, Kevin Wolf, 2014/12/16
- Re: [Qemu-devel] [PATCH v2 1/5] linux-aio: queue requests that cannot be submitted, Paolo Bonzini, 2014/12/16
- Re: [Qemu-devel] [PATCH v2 1/5] linux-aio: queue requests that cannot be submitted, Paolo Bonzini, 2014/12/16
- Re: [Qemu-devel] [PATCH v2 1/5] linux-aio: queue requests that cannot be submitted, Paolo Bonzini, 2014/12/17
- Re: [Qemu-devel] [PATCH v2 1/5] linux-aio: queue requests that cannot be submitted, Paolo Bonzini, 2014/12/17
[Qemu-devel] [PATCH v2 2/5] linux-aio: track whether the queue is blocked,
Paolo Bonzini <=
[Qemu-devel] [PATCH v2 4/5] linux-aio: drop return code from laio_io_unplug and ioq_submit, Paolo Bonzini, 2014/12/11
[Qemu-devel] [PATCH v2 5/5] linux-aio: simplify removal of completed iocbs from the list, Paolo Bonzini, 2014/12/11
[Qemu-devel] [PATCH v2 3/5] linux-aio: rename LaioQueue idx field to "n", Paolo Bonzini, 2014/12/11
Re: [Qemu-devel] [PATCH v2 0/5] linux-aio: rewrite and simplify queuing code, Kevin Wolf, 2014/12/11
Re: [Qemu-devel] [PATCH v2 0/5] linux-aio: rewrite and simplify queuing code, Stefan Hajnoczi, 2014/12/12