From: Avi Kivity <avi@redhat.com>
To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: Kevin Wolf <kwolf@redhat.com>,
qemu-devel@nongnu.org, kvm@vger.kernel.org,
Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH +stable] block: don't attempt to merge overlapping requests
Date: Wed, 19 May 2010 11:09:07 +0300 [thread overview]
Message-ID: <4BF39CA3.9020305@redhat.com> (raw)
In-Reply-To: <AANLkTilrq4KanGzUrMZFHzYIgtncUOj24dqMi_eyLdgb@mail.gmail.com>
On 05/18/2010 10:22 PM, Stefan Hajnoczi wrote:
> On Tue, May 18, 2010 at 6:18 PM, Avi Kivity<avi@redhat.com> wrote:
>
>> The block multiwrite code pretends to be able to merge overlapping requests,
>> but doesn't do so in fact. This leads to I/O errors (for example on mkfs
>> of a large virtio disk).
>>
> Are overlapping write requests correct guest behavior? I thought the
> ordering semantics require a flush between overlapping writes to
> ensure A is written before B.
>
> What cache= mode are you running?
>
writeback.
--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.
WARNING: multiple messages have this Message-ID (diff)
From: Avi Kivity <avi@redhat.com>
To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: Kevin Wolf <kwolf@redhat.com>,
qemu-devel@nongnu.org, kvm@vger.kernel.org,
Christoph Hellwig <hch@lst.de>
Subject: [Qemu-devel] Re: [PATCH +stable] block: don't attempt to merge overlapping requests
Date: Wed, 19 May 2010 11:09:07 +0300 [thread overview]
Message-ID: <4BF39CA3.9020305@redhat.com> (raw)
In-Reply-To: <AANLkTilrq4KanGzUrMZFHzYIgtncUOj24dqMi_eyLdgb@mail.gmail.com>
On 05/18/2010 10:22 PM, Stefan Hajnoczi wrote:
> On Tue, May 18, 2010 at 6:18 PM, Avi Kivity<avi@redhat.com> wrote:
>
>> The block multiwrite code pretends to be able to merge overlapping requests,
>> but doesn't do so in fact. This leads to I/O errors (for example on mkfs
>> of a large virtio disk).
>>
> Are overlapping write requests correct guest behavior? I thought the
> ordering semantics require a flush between overlapping writes to
> ensure A is written before B.
>
> What cache= mode are you running?
>
writeback.
--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.
next prev parent reply other threads:[~2010-05-19 8:09 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-18 17:18 [PATCH +stable] block: don't attempt to merge overlapping requests Avi Kivity
2010-05-18 17:18 ` [Qemu-devel] " Avi Kivity
2010-05-18 19:22 ` Stefan Hajnoczi
2010-05-18 19:22 ` [Qemu-devel] " Stefan Hajnoczi
2010-05-18 19:37 ` Stefan Hajnoczi
2010-05-18 19:37 ` [Qemu-devel] " Stefan Hajnoczi
2010-05-18 19:41 ` Michael Tokarev
2010-05-18 19:41 ` [Qemu-devel] " Michael Tokarev
2010-05-18 20:19 ` Stefan Hajnoczi
2010-05-18 20:19 ` [Qemu-devel] " Stefan Hajnoczi
2010-05-19 8:09 ` Avi Kivity [this message]
2010-05-19 8:09 ` Avi Kivity
2010-05-19 9:01 ` Stefan Hajnoczi
2010-05-19 9:01 ` [Qemu-devel] " Stefan Hajnoczi
2010-05-19 9:06 ` Avi Kivity
2010-05-19 9:06 ` [Qemu-devel] " Avi Kivity
2010-05-19 9:23 ` Stefan Hajnoczi
2010-05-19 9:23 ` [Qemu-devel] " Stefan Hajnoczi
2010-05-19 9:31 ` Christoph Hellwig
2010-05-19 9:31 ` [Qemu-devel] " Christoph Hellwig
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