From: Anthony Liguori <anthony@codemonkey.ws>
To: Avi Kivity <avi@redhat.com>
Cc: Anthony Liguori <aliguori@us.ibm.com>,
qemu-devel <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] Re: [Qemu-commits] [COMMIT 3086844] Instead of writing a zero page, madvise it away
Date: Mon, 22 Jun 2009 11:25:27 -0500 [thread overview]
Message-ID: <4A3FB077.4040607@codemonkey.ws> (raw)
In-Reply-To: <4A3FAD69.60507@redhat.com>
Avi Kivity wrote:
> On 06/22/2009 06:51 PM, Anthony Liguori wrote:
>> From: Anthony Liguori<aliguori@us.ibm.com>
>>
>> Otherwise, after migration, we end up with a much larger RSS size
>> then we
>> ought to have.
>>
>>
>
> We have the same issue on the migration source node. I don't see a
> simple way to solve it, though.
I don't follow. In this case, the issue is:
1) Start a guest with 1024, balloon down to 128MB. RSS size is now ~128MB
2) Live migrate to a different node
3) RSS on different node jumps to ~1GB
4) Weep at all your lost memory
Xen had a similar issue. This ends up biting people who overcommit
their VMs via ballooning, live migration, and badness ensues. At least
for us, the error is swapping but madvise also avoids the issue by never
consuming that memory to begin with.
Regards,
Anthony Liguori
next prev parent reply other threads:[~2009-06-22 16:25 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <200906221549.n5MFn3Qd015389@d03av02.boulder.ibm.com>
2009-06-22 16:12 ` [Qemu-devel] Re: [Qemu-commits] [COMMIT 3086844] Instead of writing a zero page, madvise it away Avi Kivity
2009-06-22 16:25 ` Anthony Liguori [this message]
2009-06-22 16:38 ` Avi Kivity
2009-06-22 16:58 ` Anthony Liguori
2009-06-22 17:12 ` Avi Kivity
2009-06-22 17:03 ` Anthony Liguori
2009-06-22 17:20 ` Avi Kivity
2009-06-22 17:37 ` Anthony Liguori
2009-06-22 18:01 ` Avi Kivity
2009-06-22 17:44 ` Anthony Liguori
2009-06-22 18:04 ` Avi Kivity
2009-06-22 19:38 ` Paul Brook
2009-06-22 19:49 ` Anthony Liguori
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