* [Qemu-devel] [PATCH for-2.3] raw-posix: Deprecate aio=threads fallback without O_DIRECT
@ 2015-03-17 12:48 Kevin Wolf
2015-03-17 14:18 ` Markus Armbruster
2015-03-17 14:22 ` [Qemu-devel] [Qemu-block] " Eric Blake
0 siblings, 2 replies; 3+ messages in thread
From: Kevin Wolf @ 2015-03-17 12:48 UTC (permalink / raw)
To: qemu-block; +Cc: kwolf, famz, armbru, qemu-devel
Currently, if the user requests aio=native, but forgets to choose a
cache mode that sets O_DIRECT, that request is silently ignored and raw
falls back to aio=threads.
Deprecate that behaviour so we can make it an error in future qemu
versions.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
block/raw-posix.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/block/raw-posix.c b/block/raw-posix.c
index f0b4488..929b6ae 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -503,6 +503,14 @@ static int raw_open_common(BlockDriverState *bs, QDict *options,
error_setg_errno(errp, -ret, "Could not set AIO state");
goto fail;
}
+ if (!s->use_aio && (bdrv_flags & BDRV_O_NATIVE_AIO)) {
+ fprintf(stderr, "WARNING: aio=native was specified for '%s', but "
+ "it requires cache.direct=on, which was not "
+ "specified. Falling back to aio=threads.\n"
+ " This will become an error condition in "
+ "future QEMU versions.\n",
+ bs->filename);
+ }
#endif
s->has_discard = true;
--
1.8.3.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [Qemu-devel] [PATCH for-2.3] raw-posix: Deprecate aio=threads fallback without O_DIRECT
2015-03-17 12:48 [Qemu-devel] [PATCH for-2.3] raw-posix: Deprecate aio=threads fallback without O_DIRECT Kevin Wolf
@ 2015-03-17 14:18 ` Markus Armbruster
2015-03-17 14:22 ` [Qemu-devel] [Qemu-block] " Eric Blake
1 sibling, 0 replies; 3+ messages in thread
From: Markus Armbruster @ 2015-03-17 14:18 UTC (permalink / raw)
To: Kevin Wolf; +Cc: famz, qemu-devel, qemu-block
Kevin Wolf <kwolf@redhat.com> writes:
> Currently, if the user requests aio=native, but forgets to choose a
> cache mode that sets O_DIRECT, that request is silently ignored and raw
> falls back to aio=threads.
>
> Deprecate that behaviour so we can make it an error in future qemu
> versions.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> block/raw-posix.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/block/raw-posix.c b/block/raw-posix.c
> index f0b4488..929b6ae 100644
> --- a/block/raw-posix.c
> +++ b/block/raw-posix.c
> @@ -503,6 +503,14 @@ static int raw_open_common(BlockDriverState *bs, QDict *options,
> error_setg_errno(errp, -ret, "Could not set AIO state");
> goto fail;
> }
> + if (!s->use_aio && (bdrv_flags & BDRV_O_NATIVE_AIO)) {
> + fprintf(stderr, "WARNING: aio=native was specified for '%s', but "
> + "it requires cache.direct=on, which was not "
> + "specified. Falling back to aio=threads.\n"
> + " This will become an error condition in "
> + "future QEMU versions.\n",
> + bs->filename);
> + }
> #endif
>
> s->has_discard = true;
error_report(), please, because:
* No warning in a monitor that isn't on the tty:
$ socat UNIX:test-hmp STDIO
QEMU 2.2.50 monitor - type 'help' for more information
(qemu) drive_add "" if=none,aio=native,file=tmp.qcow2
drive_add "" if=none,aio=native,file=tmp.qcow2
OK
* The warning gives no clue on location. Not nice when the culprit is
actually deep in some -readconfig file.
A quick grep counts 42 instances of "warning:', 53 '"Warning:', and 20
'"WARNING:'. We suck at consistency :)
For a COW image, I get the warning twice, and once for image, and once
for the backing image:
$ qemu-system-x86_64 -nodefaults -drive if=none,aio=native,file=tmp.qcow2
WARNING: aio=native was specified for 'tmp.qcow2', but it requires cache.direct=on, which was not specified. Falling back to aio=threads.
This will become an error condition in future QEMU versions.
WARNING: aio=native was specified for 'tmp.img', but it requires cache.direct=on, which was not specified. Falling back to aio=threads.
This will become an error condition in future QEMU versions.
Not sure whether this can or should be avoided.
With error_report() instead of fprintf():
Reviewed-by: Markus Armbruster <armbru@redhat.com>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [Qemu-devel] [Qemu-block] [PATCH for-2.3] raw-posix: Deprecate aio=threads fallback without O_DIRECT
2015-03-17 12:48 [Qemu-devel] [PATCH for-2.3] raw-posix: Deprecate aio=threads fallback without O_DIRECT Kevin Wolf
2015-03-17 14:18 ` Markus Armbruster
@ 2015-03-17 14:22 ` Eric Blake
1 sibling, 0 replies; 3+ messages in thread
From: Eric Blake @ 2015-03-17 14:22 UTC (permalink / raw)
To: Kevin Wolf, qemu-block; +Cc: famz, armbru, qemu-devel
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On 03/17/2015 06:48 AM, Kevin Wolf wrote:
> Currently, if the user requests aio=native, but forgets to choose a
> cache mode that sets O_DIRECT, that request is silently ignored and raw
> falls back to aio=threads.
>
> Deprecate that behaviour so we can make it an error in future qemu
> versions.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> block/raw-posix.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
Silent behavior changes are always mean, so making this noisy for now
with the intent of an error in the future is good.
Reviewed-by: Eric Blake <eblake@redhat.com>
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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^ permalink raw reply [flat|nested] 3+ messages in thread
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2015-03-17 12:48 [Qemu-devel] [PATCH for-2.3] raw-posix: Deprecate aio=threads fallback without O_DIRECT Kevin Wolf
2015-03-17 14:18 ` Markus Armbruster
2015-03-17 14:22 ` [Qemu-devel] [Qemu-block] " Eric Blake
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