Re: [PATCH] kvm: add oom notifier for virtio balloon

From: Dave Young
Date: Fri Oct 08 2010 - 06:24:29 EST


On Wed, Oct 6, 2010 at 9:50 PM, Dave Young <hidave.darkstar@xxxxxxxxx> wrote:
> On Wed, Oct 6, 2010 at 5:05 PM, Rusty Russell <rusty@xxxxxxxxxxxxxxx> wrote:
>> On Tue, 5 Oct 2010 11:15:21 pm Dave Young wrote:
>>> Balloon could cause guest memory oom killing and panic.
>>>
>>> Add oom notify to leak some memory and retry fill balloon after 5 minutes.
>>
>> Have you tried registering a shrinker? ÂSee mm.h.
>
> Hi, thanks. I didn't know shrinker can shrink mem beyond slab. Will try
Hi, rusty

I did some test with shrinker, findings as following:

1. shrinker is for ageable cache shrinking, balloon pages is a different kind
2. oom notifier is a last minute shrink, but shrinker is more conservative.
after my tests of "balloon 30" for a slackware 13.0 guest, free -m in guest
oom notifier results 17M
shrinker results 77M

3. Aside of above use mutex locking in shrinker cause kernel hang, no
idea how to fix it


>
>>
>> Thanks,
>> Rusty.
>>
>
>
>
> --
> Regards
> dave
>



--
Regards
dave
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