From: Anthony Liguori <aliguori@us.ibm.com>
To: Avi Kivity <avi@redhat.com>
Cc: "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
kvm-devel <kvm@vger.kernel.org>
Subject: Re: Live migration broken when under heavy IO
Date: Tue, 16 Jun 2009 07:50:12 -0500 [thread overview]
Message-ID: <4A379504.4080100@us.ibm.com> (raw)
In-Reply-To: <4A37618E.6040606@redhat.com>
Avi Kivity wrote:
>> Does anyone have a clever idea how to fix this without just waiting
>> for all IO requests to complete?
>
> What's wrong with waiting for requests to complete? It should take a
> few tens of milliseconds.
An alternative would be to attempt to cancel the requests. This incurs
no non-deterministic latency.
The tricky bit is that this has to happen at the device layer because
the opaques cannot be saved in a meaningful way.
> We could start throttling requests late in the live stage, but I don't
> really see the point.
>
> Isn't virtio migration currently broken due to the qdev changes?
>
--
Regards,
Anthony Liguori
WARNING: multiple messages have this Message-ID (diff)
From: Anthony Liguori <aliguori@us.ibm.com>
To: Avi Kivity <avi@redhat.com>
Cc: "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
kvm-devel <kvm@vger.kernel.org>
Subject: [Qemu-devel] Re: Live migration broken when under heavy IO
Date: Tue, 16 Jun 2009 07:50:12 -0500 [thread overview]
Message-ID: <4A379504.4080100@us.ibm.com> (raw)
In-Reply-To: <4A37618E.6040606@redhat.com>
Avi Kivity wrote:
>> Does anyone have a clever idea how to fix this without just waiting
>> for all IO requests to complete?
>
> What's wrong with waiting for requests to complete? It should take a
> few tens of milliseconds.
An alternative would be to attempt to cancel the requests. This incurs
no non-deterministic latency.
The tricky bit is that this has to happen at the device layer because
the opaques cannot be saved in a meaningful way.
> We could start throttling requests late in the live stage, but I don't
> really see the point.
>
> Isn't virtio migration currently broken due to the qdev changes?
>
--
Regards,
Anthony Liguori
next prev parent reply other threads:[~2009-06-16 12:50 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-06-15 20:33 Live migration broken when under heavy IO Anthony Liguori
2009-06-15 20:33 ` [Qemu-devel] " Anthony Liguori
2009-06-15 20:48 ` Glauber Costa
2009-06-16 9:10 ` Avi Kivity
2009-06-16 9:10 ` [Qemu-devel] " Avi Kivity
2009-06-16 9:13 ` Avi Kivity
2009-06-16 9:13 ` [Qemu-devel] " Avi Kivity
2009-06-16 12:50 ` Anthony Liguori [this message]
2009-06-16 12:50 ` Anthony Liguori
2009-06-16 12:54 ` Avi Kivity
2009-06-16 12:54 ` [Qemu-devel] " Avi Kivity
2009-06-16 12:57 ` Anthony Liguori
2009-06-16 12:57 ` [Qemu-devel] " Anthony Liguori
2009-06-16 13:12 ` Avi Kivity
2009-06-16 13:12 ` [Qemu-devel] " Avi Kivity
2009-06-16 18:19 ` Charles Duffy
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