From: Avi Kivity <avi@redhat.com>
To: Anthony Liguori <aliguori@us.ibm.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 15:54:12 +0300 [thread overview]
Message-ID: <4A3795F4.9080507@redhat.com> (raw)
In-Reply-To: <4A379504.4080100@us.ibm.com>
On 06/16/2009 03:50 PM, Anthony Liguori wrote:
> 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.
Yes, that's even better (though without linux-aio, it's equivalent).
>
> The tricky bit is that this has to happen at the device layer because
> the opaques cannot be saved in a meaningful way.
>
Do you mean the device has to record all cancelled requests and replay
them? I think we can do it at the block layer (though we have to avoid
it for nested requests).
--
error compiling committee.c: too many arguments to function
WARNING: multiple messages have this Message-ID (diff)
From: Avi Kivity <avi@redhat.com>
To: Anthony Liguori <aliguori@us.ibm.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 15:54:12 +0300 [thread overview]
Message-ID: <4A3795F4.9080507@redhat.com> (raw)
In-Reply-To: <4A379504.4080100@us.ibm.com>
On 06/16/2009 03:50 PM, Anthony Liguori wrote:
> 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.
Yes, that's even better (though without linux-aio, it's equivalent).
>
> The tricky bit is that this has to happen at the device layer because
> the opaques cannot be saved in a meaningful way.
>
Do you mean the device has to record all cancelled requests and replay
them? I think we can do it at the block layer (though we have to avoid
it for nested requests).
--
error compiling committee.c: too many arguments to function
next prev parent reply other threads:[~2009-06-16 12:54 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
2009-06-16 12:50 ` [Qemu-devel] " Anthony Liguori
2009-06-16 12:54 ` Avi Kivity [this message]
2009-06-16 12:54 ` 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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