From: Martin Mailand <martin@tuxadero.com>
To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: Dongsu Park <dongsu.park@profitbricks.com>,
qemu-devel@nongnu.org, kvm@vger.kernel.org
Subject: Re: virtio-blk performance regression and qemu-kvm
Date: Tue, 28 Feb 2012 17:39:54 +0100 [thread overview]
Message-ID: <4F4D035A.60107@tuxadero.com> (raw)
In-Reply-To: <CAJSP0QUKiKaKuQL46w3cycxL=cYgqUD=cc+MZCL=arKbMUZx0g@mail.gmail.com>
Hi,
I could reproduce it and I bisected it down to this commit.
12d4536f7d911b6d87a766ad7300482ea663cea2 is the first bad commit
commit 12d4536f7d911b6d87a766ad7300482ea663cea2
Author: Anthony Liguori <aliguori@us.ibm.com>
Date: Mon Aug 22 08:24:58 2011 -0500
-martin
On 22.02.2012 20:53, Stefan Hajnoczi wrote:
> On Wed, Feb 22, 2012 at 4:48 PM, Dongsu Park
> <dongsu.park@profitbricks.com> wrote:
>>> Try turning ioeventfd off for the virtio-blk device:
>>>
>>> -device virtio-blk-pci,ioeventfd=off,...
>>>
>>> You might see better performance since ramdisk I/O should be very
>>> low-latency. The overhead of using ioeventfd might not make it
>>> worthwhile. The ioeventfd feature was added post-0.14 IIRC. Normally
>>> it helps avoid stealing vcpu time and also causing lock contention
>>> inside the guest - but if host I/O latency is extremely low it might
>>> be faster to issue I/O from the vcpu thread.
>> Thanks for the tip. I tried that too, but no success.
> My guesses have all been wrong. Maybe it's time to git bisect this instead :).
>
> Stefan
> --
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next prev parent reply other threads:[~2012-02-28 16:40 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-10 14:36 virtio-blk performance regression and qemu-kvm Dongsu Park
2012-02-12 23:55 ` Rusty Russell
2012-02-21 16:45 ` Dongsu Park
2012-02-21 22:16 ` Rusty Russell
2012-02-13 11:57 ` Stefan Hajnoczi
2012-02-21 15:57 ` Dongsu Park
2012-02-21 17:27 ` Stefan Hajnoczi
2012-02-22 16:48 ` Dongsu Park
2012-02-22 19:53 ` Stefan Hajnoczi
2012-02-28 16:39 ` Martin Mailand [this message]
2012-02-28 17:05 ` Stefan Hajnoczi
2012-02-28 17:15 ` Martin Mailand
2012-02-29 8:38 ` Stefan Hajnoczi
2012-02-29 13:12 ` Martin Mailand
2012-02-29 13:44 ` Stefan Hajnoczi
2012-02-29 13:52 ` Stefan Hajnoczi
2012-03-05 16:13 ` Martin Mailand
2012-03-05 16:35 ` Stefan Hajnoczi
2012-03-05 16:44 ` Martin Mailand
2012-03-06 12:59 ` Stefan Hajnoczi
2012-03-06 22:07 ` [Qemu-devel] " Reeted
2012-03-07 8:04 ` Stefan Hajnoczi
2012-03-07 14:21 ` Reeted
2012-03-07 14:33 ` Stefan Hajnoczi
2012-03-07 10:39 ` Martin Mailand
2012-03-07 11:21 ` Paolo Bonzini
2012-03-06 14:32 ` Dongsu Park
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