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 12:06:38 +0300 [thread overview]
Message-ID: <4BF3AA1E.4050307@redhat.com> (raw)
In-Reply-To: <AANLkTimrA6drQrxHtp5lGF10uPuV1pSgzZdgut-6oami@mail.gmail.com>
On 05/19/2010 12:01 PM, Stefan Hajnoczi wrote:
> On Wed, May 19, 2010 at 9:09 AM, Avi Kivity<avi@redhat.com> wrote:
>
>> On 05/18/2010 10:22 PM, Stefan Hajnoczi wrote:
>>
>>> What cache= mode are you running?
>>>
>> writeback.
>>
> In the cache=writeback case the virtio-blk guest driver does:
>
> blk_queue_ordered(q, QUEUE_ORDERED_DRAIN_FLUSH, ...)
>
I don't follow. What's the implication?
btw I really dislike how the cache attribute (which I see as a pure host
choice) is exposed to the guest. It means we can't change caching mode
on the fly (for example after live migration), or that changing caching
mode during a restart may expose a previously hidden guest bug.
--
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 9:06 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-18 17:18 [Qemu-devel] [PATCH +stable] block: don't attempt to merge overlapping requests Avi Kivity
2010-05-18 19:22 ` [Qemu-devel] " Stefan Hajnoczi
2010-05-18 19:37 ` Stefan Hajnoczi
2010-05-18 19:41 ` Michael Tokarev
2010-05-18 20:19 ` Stefan Hajnoczi
2010-05-19 8:09 ` Avi Kivity
2010-05-19 9:01 ` Stefan Hajnoczi
2010-05-19 9:06 ` Avi Kivity [this message]
2010-05-19 9:23 ` Stefan Hajnoczi
2010-05-19 9:31 ` Christoph Hellwig
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