Re: [Qemu-devel] [PATCH] blockdev: warn about aio=native if libaio is unavailable
On Fri, Jul 17, 2015 at 12:56:15PM +0200, Kevin Wolf wrote: Am 17.07.2015 um 11:59 hat Stefan Hajnoczi geschrieben: QEMU silently ignores aio=native if libaio is unavailable. It is confusing when aio=native performance is identical to aio=threads because the binary was accidentally built without libaio. Use error_report() because failing would break backward compatibility. There are probably users using aio=native who would be inconvenienced if QEMU suddenly refused to start their guests. Signed-off-by: Stefan Hajnoczi stefa...@redhat.com I hope not too many people are using aio=native without having libaio compiled in... Can we make it a message like for the case with aio=native,cache.direct=off, i.e. a deprecation warning that allows us to make this an error in a few releases? Yes, I'll move the warning to raw-posix.c so all callers benefit from it. pgpoOON4yc1s8.pgp Description: PGP signature
[Qemu-devel] [PATCH] blockdev: warn about aio=native if libaio is unavailable
QEMU silently ignores aio=native if libaio is unavailable. It is
confusing when aio=native performance is identical to aio=threads
because the binary was accidentally built without libaio.
Use error_report() because failing would break backward compatibility.
There are probably users using aio=native who would be inconvenienced if
QEMU suddenly refused to start their guests.
Signed-off-by: Stefan Hajnoczi stefa...@redhat.com
---
blockdev.c | 7 +--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/blockdev.c b/blockdev.c
index 62a4586..f30828a 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -405,10 +405,14 @@ static BlockBackend *blockdev_init(const char *file,
QDict *bs_opts,
bdrv_flags |= BDRV_O_NO_FLUSH;
}
-#ifdef CONFIG_LINUX_AIO
if ((buf = qemu_opt_get(opts, aio)) != NULL) {
if (!strcmp(buf, native)) {
+#ifdef CONFIG_LINUX_AIO
bdrv_flags |= BDRV_O_NATIVE_AIO;
+#else
+error_report(warning: aio=native support unavailable,
+ using default instead);
+#endif
} else if (!strcmp(buf, threads)) {
/* this is the default */
} else {
@@ -416,7 +420,6 @@ static BlockBackend *blockdev_init(const char *file, QDict
*bs_opts,
goto early_err;
}
}
-#endif
if ((buf = qemu_opt_get(opts, format)) != NULL) {
if (is_help_option(buf)) {
--
2.4.3
Re: [Qemu-devel] [PATCH] blockdev: warn about aio=native if libaio is unavailable
Am 17.07.2015 um 11:59 hat Stefan Hajnoczi geschrieben:
QEMU silently ignores aio=native if libaio is unavailable. It is
confusing when aio=native performance is identical to aio=threads
because the binary was accidentally built without libaio.
Use error_report() because failing would break backward compatibility.
There are probably users using aio=native who would be inconvenienced if
QEMU suddenly refused to start their guests.
Signed-off-by: Stefan Hajnoczi stefa...@redhat.com
I hope not too many people are using aio=native without having libaio
compiled in... Can we make it a message like for the case with
aio=native,cache.direct=off, i.e. a deprecation warning that allows us
to make this an error in a few releases?
blockdev.c | 7 +--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/blockdev.c b/blockdev.c
index 62a4586..f30828a 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -405,10 +405,14 @@ static BlockBackend *blockdev_init(const char *file,
QDict *bs_opts,
bdrv_flags |= BDRV_O_NO_FLUSH;
}
-#ifdef CONFIG_LINUX_AIO
if ((buf = qemu_opt_get(opts, aio)) != NULL) {
if (!strcmp(buf, native)) {
+#ifdef CONFIG_LINUX_AIO
bdrv_flags |= BDRV_O_NATIVE_AIO;
+#else
+error_report(warning: aio=native support unavailable,
+ using default instead);
+#endif
} else if (!strcmp(buf, threads)) {
/* this is the default */
} else {
@@ -416,7 +420,6 @@ static BlockBackend *blockdev_init(const char *file,
QDict *bs_opts,
goto early_err;
}
}
-#endif
*sigh* It's sad to see that we still have such code in the generic block
layer. It has no business there, the raw-posix driver should check
whether it can support Linux AIO or not.
Paolo: You added some code to raw-win32 that implements aio=native.
Did it ever work in qemu proper, or only in the tools? It doesn't seem
that this code would even have added the flag on Windows builds.
Kevin
