From: Anthony Liguori <anthony@codemonkey.ws>
To: Michael Tokarev <mjt@tls.msk.ru>
Cc: Christoph Hellwig <hch@infradead.org>,
KVM list <kvm@vger.kernel.org>, Kevin Wolf <kwolf@redhat.com>
Subject: Re: JFYI: ext4 bug triggerable by kvm
Date: Tue, 17 Aug 2010 09:44:49 -0500 [thread overview]
Message-ID: <4C6AA061.80704@codemonkey.ws> (raw)
In-Reply-To: <4C6A9F4F.8040209@msgid.tls.msk.ru>
On 08/17/2010 09:40 AM, Michael Tokarev wrote:
>
>>> fsync() being slow is orthogonal to my point. I don't see why we
>>> need to do an fsync() on *every* write. It should only be necessary
>>> when a guest injects an actual barrier.
>>>
> We don't do sync on every write, but O_SYNC implies that.
> And apparently it is what happening behind the scenes in
> ext4 O_SYNC case.
>
I think the real issue is we're mixing host configuration with guest
visible state.
With O_SYNC, we're causing cache=writethrough to do writethrough through
two layers of the storage heirarchy. I don't think that's necessary or
desirable though.
Regards,
Anthony Liguori
> But ok....
>
> /mjt
>
next prev parent reply other threads:[~2010-08-17 14:44 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-16 14:00 JFYI: ext4 bug triggerable by kvm Michael Tokarev
2010-08-16 14:43 ` Anthony Liguori
2010-08-16 18:42 ` Christoph Hellwig
2010-08-16 20:34 ` Anthony Liguori
2010-08-17 9:07 ` Christoph Hellwig
2010-08-17 9:23 ` Avi Kivity
2010-08-17 11:17 ` Christoph Hellwig
2010-08-17 12:56 ` Anthony Liguori
2010-08-17 13:07 ` Christoph Hellwig
2010-08-17 14:20 ` Anthony Liguori
2010-08-17 14:28 ` Christoph Hellwig
2010-08-17 14:39 ` Anthony Liguori
2010-08-17 14:45 ` Christoph Hellwig
2010-08-17 14:53 ` Avi Kivity
2010-08-17 14:54 ` Anthony Liguori
2010-08-17 15:01 ` Avi Kivity
2010-08-17 15:02 ` Christoph Hellwig
2010-08-17 14:40 ` Michael Tokarev
2010-08-17 14:44 ` Anthony Liguori [this message]
2010-08-17 14:46 ` Christoph Hellwig
2010-08-17 14:57 ` Anthony Liguori
2010-08-17 14:59 ` Avi Kivity
2010-08-17 15:04 ` Christoph Hellwig
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