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[Qemu-devel] [PULL 47/48] aio: make aio_poll(ctx, true) block with no fd
From: |
Stefan Hajnoczi |
Subject: |
[Qemu-devel] [PULL 47/48] aio: make aio_poll(ctx, true) block with no fds |
Date: |
Fri, 6 Dec 2013 17:36:46 +0100 |
This patch drops a special case where aio_poll(ctx, true) returns false
instead of blocking if no file descriptors are waiting on I/O. Now it
is possible to block in aio_poll() to wait for aio_notify().
This change eliminates busy waiting. bdrv_drain_all() used to rely on
busy waiting to completed throttled I/O requests but this is no longer
required so we can simplify aio_poll().
Note that aio_poll() still returns false when aio_notify() was used. In
other words, stopping a blocking aio_poll() wait is not considered
making progress.
Adjust test-aio /aio/bh/callback-delete/one which assumed aio_poll(ctx,
true) would immediately return false instead of blocking.
Reviewed-by: Alex Bligh <address@hidden>
Signed-off-by: Stefan Hajnoczi <address@hidden>
---
aio-posix.c | 5 -----
aio-win32.c | 5 -----
tests/test-aio.c | 1 -
3 files changed, 11 deletions(-)
diff --git a/aio-posix.c b/aio-posix.c
index bd06f33..f921d4f 100644
--- a/aio-posix.c
+++ b/aio-posix.c
@@ -217,11 +217,6 @@ bool aio_poll(AioContext *ctx, bool blocking)
ctx->walking_handlers--;
- /* early return if we only have the aio_notify() fd */
- if (ctx->pollfds->len == 1) {
- return progress;
- }
-
/* wait until next event */
ret = qemu_poll_ns((GPollFD *)ctx->pollfds->data,
ctx->pollfds->len,
diff --git a/aio-win32.c b/aio-win32.c
index f9cfbb7..23f4e5b 100644
--- a/aio-win32.c
+++ b/aio-win32.c
@@ -161,11 +161,6 @@ bool aio_poll(AioContext *ctx, bool blocking)
ctx->walking_handlers--;
- /* early return if we only have the aio_notify() fd */
- if (count == 1) {
- return progress;
- }
-
/* wait until next event */
while (count > 0) {
int ret;
diff --git a/tests/test-aio.c b/tests/test-aio.c
index c4fe0fc..592721e 100644
--- a/tests/test-aio.c
+++ b/tests/test-aio.c
@@ -195,7 +195,6 @@ static void test_bh_delete_from_cb(void)
g_assert(data1.bh == NULL);
g_assert(!aio_poll(ctx, false));
- g_assert(!aio_poll(ctx, true));
}
static void test_bh_delete_from_cb_many(void)
--
1.8.4.2
- [Qemu-devel] [PULL 36/48] qemu-nbd: add doc for option -f, (continued)
- [Qemu-devel] [PULL 36/48] qemu-nbd: add doc for option -f, Stefan Hajnoczi, 2013/12/06
- [Qemu-devel] [PULL 37/48] qemu-img: add support for skipping zeroes in input during convert, Stefan Hajnoczi, 2013/12/06
- [Qemu-devel] [PULL 38/48] qemu-img: fix usage instruction for qemu-img convert, Stefan Hajnoczi, 2013/12/06
- [Qemu-devel] [PULL 39/48] block/iscsi: set bdi->cluster_size, Stefan Hajnoczi, 2013/12/06
- [Qemu-devel] [PULL 40/48] block: add opt_transfer_length to BlockLimits, Stefan Hajnoczi, 2013/12/06
- [Qemu-devel] [PULL 41/48] block/iscsi: set bs->bl.opt_transfer_length, Stefan Hajnoczi, 2013/12/06
- [Qemu-devel] [PULL 42/48] qemu-img: dynamically adjust iobuffer size during convert, Stefan Hajnoczi, 2013/12/06
- [Qemu-devel] [PULL 43/48] qemu-img: round down request length to an aligned sector, Stefan Hajnoczi, 2013/12/06
- [Qemu-devel] [PULL 44/48] qemu-img: decrease progress update interval on convert, Stefan Hajnoczi, 2013/12/06
- [Qemu-devel] [PULL 46/48] block: clean up bdrv_drain_all() throttling comments, Stefan Hajnoczi, 2013/12/06
- [Qemu-devel] [PULL 47/48] aio: make aio_poll(ctx, true) block with no fds,
Stefan Hajnoczi <=
- [Qemu-devel] [PULL 48/48] qemu-iotests: filter QEMU monitor \r\n, Stefan Hajnoczi, 2013/12/06
- [Qemu-devel] [PULL 45/48] qcow2: use start_of_cluster() and offset_into_cluster() everywhere, Stefan Hajnoczi, 2013/12/06
- [Qemu-devel] [PULL 31/48] snapshot: distinguish id and name in load_tmp, Stefan Hajnoczi, 2013/12/06