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[Qemu-devel] [RFC 01/13] block: stop relying on io_flush() in bdrv_drain
From: |
Stefan Hajnoczi |
Subject: |
[Qemu-devel] [RFC 01/13] block: stop relying on io_flush() in bdrv_drain_all() |
Date: |
Thu, 11 Apr 2013 17:44:33 +0200 |
If a block driver has no file descriptors to monitor but there are still
active requests, it can return 1 from .io_flush(). This is used to spin
during synchronous I/O.
Stop relying on .io_flush() and instead check
QLIST_EMPTY(&bs->tracked_requests) to decide whether there are active
requests.
This is the first step in removing .io_flush() so that event loops no
longer need to have the concept of synchronous I/O. Eventually we may
be able to kill synchronous I/O completely by running everything in a
coroutine, but that is future work.
Signed-off-by: Stefan Hajnoczi <address@hidden>
---
block.c | 28 ++++++++++++++++++----------
1 file changed, 18 insertions(+), 10 deletions(-)
diff --git a/block.c b/block.c
index 602d8a4..93d676b 100644
--- a/block.c
+++ b/block.c
@@ -1360,6 +1360,22 @@ void bdrv_close_all(void)
}
}
+/* Check if any requests are in-flight (including throttled requests) */
+static bool bdrv_requests_pending(void)
+{
+ BlockDriverState *bs;
+
+ QTAILQ_FOREACH(bs, &bdrv_states, list) {
+ if (!QLIST_EMPTY(&bs->tracked_requests)) {
+ return true;
+ }
+ if (!qemu_co_queue_empty(&bs->throttled_reqs)) {
+ return true;
+ }
+ }
+ return false;
+}
+
/*
* Wait for pending requests to complete across all BlockDriverStates
*
@@ -1375,26 +1391,18 @@ void bdrv_close_all(void)
void bdrv_drain_all(void)
{
BlockDriverState *bs;
- bool busy;
-
- do {
- busy = qemu_aio_wait();
+ while (bdrv_requests_pending()) {
/* FIXME: We do not have timer support here, so this is effectively
* a busy wait.
*/
QTAILQ_FOREACH(bs, &bdrv_states, list) {
if (!qemu_co_queue_empty(&bs->throttled_reqs)) {
qemu_co_queue_restart_all(&bs->throttled_reqs);
- busy = true;
}
}
- } while (busy);
- /* If requests are still pending there is a bug somewhere */
- QTAILQ_FOREACH(bs, &bdrv_states, list) {
- assert(QLIST_EMPTY(&bs->tracked_requests));
- assert(qemu_co_queue_empty(&bs->throttled_reqs));
+ qemu_aio_wait();
}
}
--
1.8.1.4
- [Qemu-devel] [RFC 00/13] aio: drop io_flush(), Stefan Hajnoczi, 2013/04/11
- [Qemu-devel] [RFC 03/13] aio: stop using .io_flush(), Stefan Hajnoczi, 2013/04/11
- [Qemu-devel] [RFC 07/13] block/linux-aio: drop qemu_laio_completion_cb(), Stefan Hajnoczi, 2013/04/11
- [Qemu-devel] [RFC 11/13] dataplane/virtio-blk: drop flush_true() and flush_io(), Stefan Hajnoczi, 2013/04/11
- [Qemu-devel] [RFC 12/13] thread-pool: drop thread_pool_active(), Stefan Hajnoczi, 2013/04/11
- [Qemu-devel] [RFC 05/13] block/gluster: drop qemu_gluster_aio_flush_cb(), Stefan Hajnoczi, 2013/04/11
- [Qemu-devel] [RFC 01/13] block: stop relying on io_flush() in bdrv_drain_all(),
Stefan Hajnoczi <=
- [Qemu-devel] [RFC 10/13] block/sheepdog: drop have_co_req() and aio_flush_request(), Stefan Hajnoczi, 2013/04/11
- [Qemu-devel] [RFC 09/13] block/rbd: drop qemu_rbd_aio_flush_cb(), Stefan Hajnoczi, 2013/04/11
- [Qemu-devel] [RFC 13/13] aio: drop io_flush argument, Stefan Hajnoczi, 2013/04/11
- [Qemu-devel] [RFC 06/13] block/iscsi: drop iscsi_process_flush(), Stefan Hajnoczi, 2013/04/11
- [Qemu-devel] [RFC 04/13] block/curl: drop curl_aio_flush(), Stefan Hajnoczi, 2013/04/11
- [Qemu-devel] [RFC 08/13] block/nbd: drop nbd_have_request(), Stefan Hajnoczi, 2013/04/11
- [Qemu-devel] [RFC 02/13] dataplane/virtio-blk: check exit conditions before aio_poll(), Stefan Hajnoczi, 2013/04/11
- Re: [Qemu-devel] [RFC 00/13] aio: drop io_flush(), Kevin Wolf, 2013/04/12