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[Qemu-devel] Re: [RFC][STABLE 0.13] Revert "qcow2: Use bdrv_(p)write_syn
From: |
Juan Quintela |
Subject: |
[Qemu-devel] Re: [RFC][STABLE 0.13] Revert "qcow2: Use bdrv_(p)write_sync for metadata writes" |
Date: |
Tue, 24 Aug 2010 14:48:42 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/23.2 (gnu/linux) |
Kevin Wolf <address@hidden> wrote:
> This reverts commit 8b3b720620a1137a1b794fc3ed64734236f94e06.
>
> This fix has caused severe slowdowns on recent kernels that actually do flush
> when they are told so. Reverting this patch hurts correctness and means that
> we
> could get corrupted images in case of a host crash. This means that qcow2
> might
> not be an option for some people without this fix. On the other hand, I get
> reports that the slowdown is so massive that not reverting it would mean that
> people can't use it either because it just takes ages to complete stuff. It
> probably can be fixed, but not in time for 0.13.0.
>
> Usually, if there's a possible tradeoff between correctness and performance, I
> tend to choose correctness, but I'm not so sure in this case. I'm not sure
> with
> reverting either, which is why I post this as an RFC only.
>
> I hope to get some more comments on how to proceed here for 0.13.
I think that we have to revert also.
It is a thoug decission so. This patch makes things more "correct",
but it makes some load really slow, for instance, and install went from
15m to 50m on my hardware :(
My point here is that with the patch, qcow2 becomes almost unusable, so
... what to do?
Later, Juan.
- Re: [Qemu-devel] Re: [RFC][STABLE 0.13] Revert "qcow2: Use bdrv_(p)write_sync for metadata writes", (continued)
- Re: [Qemu-devel] Re: [RFC][STABLE 0.13] Revert "qcow2: Use bdrv_(p)write_sync for metadata writes", Kevin Wolf, 2010/08/24
- Re: [Qemu-devel] Re: [RFC][STABLE 0.13] Revert "qcow2: Use bdrv_(p)write_sync for metadata writes", Alexander Graf, 2010/08/24
- Re: [Qemu-devel] Re: [RFC][STABLE 0.13] Revert "qcow2: Use bdrv_(p)write_sync for metadata writes", Avi Kivity, 2010/08/24
- Re: [Qemu-devel] Re: [RFC][STABLE 0.13] Revert "qcow2: Use bdrv_(p)write_sync for metadata writes", Alexander Graf, 2010/08/24
- Re: [Qemu-devel] Re: [RFC][STABLE 0.13] Revert "qcow2: Use bdrv_(p)write_sync for metadata writes", Avi Kivity, 2010/08/24
- Re: [Qemu-devel] Re: [RFC][STABLE 0.13] Revert "qcow2: Use bdrv_(p)write_sync for metadata writes", Kevin Wolf, 2010/08/24
- Re: [Qemu-devel] Re: [RFC][STABLE 0.13] Revert "qcow2: Use bdrv_(p)write_sync for metadata writes", Avi Kivity, 2010/08/24
- Re: [Qemu-devel] Re: [RFC][STABLE 0.13] Revert "qcow2: Use bdrv_(p)write_sync for metadata writes", Kevin Wolf, 2010/08/24
- [Qemu-devel] Re: [RFC][STABLE 0.13] Revert "qcow2: Use bdrv_(p)write_sync for metadata writes", Stefan Hajnoczi, 2010/08/24
- [Qemu-devel] Re: [RFC][STABLE 0.13] Revert "qcow2: Use bdrv_(p)write_sync for metadata writes", Michael Tokarev, 2010/08/24
[Qemu-devel] Re: [RFC][STABLE 0.13] Revert "qcow2: Use bdrv_(p)write_sync for metadata writes",
Juan Quintela <=
[Qemu-devel] Re: [RFC][STABLE 0.13] Revert "qcow2: Use bdrv_(p)write_sync for metadata writes", Anthony Liguori, 2010/08/24
- [Qemu-devel] Re: [RFC][STABLE 0.13] Revert "qcow2: Use bdrv_(p)write_sync for metadata writes", Kevin Wolf, 2010/08/24
- [Qemu-devel] Re: [RFC][STABLE 0.13] Revert "qcow2: Use bdrv_(p)write_sync for metadata writes", Anthony Liguori, 2010/08/24
- [Qemu-devel] Re: [RFC][STABLE 0.13] Revert "qcow2: Use bdrv_(p)write_sync for metadata writes", Avi Kivity, 2010/08/24
- [Qemu-devel] Re: [RFC][STABLE 0.13] Revert "qcow2: Use bdrv_(p)write_sync for metadata writes", Anthony Liguori, 2010/08/24
- [Qemu-devel] Re: [RFC][STABLE 0.13] Revert "qcow2: Use bdrv_(p)write_sync for metadata writes", Avi Kivity, 2010/08/24
- [Qemu-devel] Re: [RFC][STABLE 0.13] Revert "qcow2: Use bdrv_(p)write_sync for metadata writes", Anthony Liguori, 2010/08/24
- [Qemu-devel] Re: [RFC][STABLE 0.13] Revert "qcow2: Use bdrv_(p)write_sync for metadata writes", Avi Kivity, 2010/08/24
- [Qemu-devel] Re: [RFC][STABLE 0.13] Revert "qcow2: Use bdrv_(p)write_sync for metadata writes", Anthony Liguori, 2010/08/24
- [Qemu-devel] Re: [RFC][STABLE 0.13] Revert "qcow2: Use bdrv_(p)write_sync for metadata writes", Avi Kivity, 2010/08/25