From: Kevin Wolf <kwolf@redhat.com>
To: Anthony Liguori <anthony@codemonkey.ws>
Cc: Chris Wright <chrisw@redhat.com>,
qemu-devel@nongnu.org, kvm@vger.kernel.org
Subject: Re: [Qemu-devel] Re: KVM call minutes for Sept 14
Date: Wed, 15 Sep 2010 15:57:44 +0200 [thread overview]
Message-ID: <4C90D0D8.6070308@redhat.com> (raw)
In-Reply-To: <4C90CFB3.1000708@codemonkey.ws>
Am 15.09.2010 15:52, schrieb Anthony Liguori:
> On 09/15/2010 08:30 AM, Kevin Wolf wrote:
>> Am 15.09.2010 15:21, schrieb Anthony Liguori:
>>
>>> On 09/15/2010 07:38 AM, Kevin Wolf wrote:
>>>
>>>> No, we don't really care if the L2 entry is on disk. If the guest want
>>>> to have its data safe it needs to issue an explicit flush anyway. The
>>>> only thing we want to achieve with bdrv_write_sync is to maintain the
>>>> right order between metadata updates to survive a crash without corruption.
>>>>
>>>>
>>> Ah, yes, this is brand new :-)
>>>
>>> I was looking at my QED branch which is a few weeks old.
>>>
>> Well, the whole bdrv_pwrite_sync thing is new - with your benchmarking
>> you probably caught qcow2 at its worst performance in years.
>
> FWIW, we queued a run reverting the sync() stuff entirely as we were
> aware of that. Should have results this morning.
Okay. I think that will be helpful, even outside the context of QED. I'd
be interested how much of a difference it really makes in your tests.
Kevin
prev parent reply other threads:[~2010-09-15 13:57 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-14 14:47 KVM call minutes for Sept 14 Chris Wright
2010-09-14 15:11 ` Anthony Liguori
2010-09-15 8:30 ` [Qemu-devel] " Kevin Wolf
2010-09-15 12:26 ` Anthony Liguori
2010-09-15 12:38 ` Kevin Wolf
2010-09-15 13:21 ` Anthony Liguori
2010-09-15 13:30 ` Kevin Wolf
2010-09-15 13:52 ` Anthony Liguori
2010-09-15 13:57 ` Kevin Wolf [this message]
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