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[Qemu-devel] [PATCH] linux aio: some comments
From: |
Frediano Ziglio |
Subject: |
[Qemu-devel] [PATCH] linux aio: some comments |
Date: |
Tue, 30 Aug 2011 09:46:11 +0200 |
Add some notes about Linux AIO explaining why we don't use AIO in
some situations.
Signed-off-by: Frediano Ziglio <address@hidden>
---
block/raw-posix.c | 4 ++++
linux-aio.c | 1 +
2 files changed, 5 insertions(+), 0 deletions(-)
diff --git a/block/raw-posix.c b/block/raw-posix.c
index c5c9944..bcf50b2 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -236,6 +236,10 @@ static int raw_open_common(BlockDriverState *bs, const
char *filename,
}
#ifdef CONFIG_LINUX_AIO
+ /*
+ * Currently Linux do AIO only for files opened with O_DIRECT
+ * specified so check NOCACHE flag too
+ */
if ((bdrv_flags & (BDRV_O_NOCACHE|BDRV_O_NATIVE_AIO)) ==
(BDRV_O_NOCACHE|BDRV_O_NATIVE_AIO)) {
diff --git a/linux-aio.c b/linux-aio.c
index 5fd3932..5265a02 100644
--- a/linux-aio.c
+++ b/linux-aio.c
@@ -181,6 +181,7 @@ BlockDriverAIOCB *laio_submit(BlockDriverState *bs, void
*aio_ctx, int fd,
case QEMU_AIO_READ:
io_prep_preadv(iocbs, fd, qiov->iov, qiov->niov, offset);
break;
+ /* Currently Linux kernel does not support other operations */
default:
fprintf(stderr, "%s: invalid AIO request type 0x%x.\n",
__func__, type);
--
1.7.1
- [Qemu-devel] [PATCH] linux aio: some comments,
Frediano Ziglio <=