Re: [Qemu-devel] [Qemu-ppc] broken incoming migration

From: Wenchao Xia <xiawenc@linux.vnet.ibm.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Alexey Kardashevskiy <aik@ozlabs.ru>, Peter Lieven <pl@kamp.de>,
	"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
	"qemu-ppc@nongnu.org" <qemu-ppc@nongnu.org>,
	David Gibson <david@gibson.dropbear.id.au>
Subject: Re: [Qemu-devel] [Qemu-ppc]  broken incoming migration
Date: Thu, 13 Jun 2013 10:41:16 +0800	[thread overview]
Message-ID: <51B9314C.3060103@linux.vnet.ibm.com> (raw)
In-Reply-To: <51B8D5BE.7080304@redhat.com>

于 2013-6-13 4:10, Paolo Bonzini 写道:
> Il 12/06/2013 10:11, Benjamin Herrenschmidt ha scritto:
>> On Wed, 2013-06-12 at 10:00 -0400, Paolo Bonzini wrote:
>>> The only bug we have is not a performance bug related to compression;
>>> it's that writing zero pages breaks overcommit.  Let's fix that, and
>>> only that.
>>
>> Right, do we have a way to madvise "throw away" these instead ?
>
> We already do that, but apparently that madvise is asynchronous.
>
>> Or do we
>> have a way to track that the platform init code did write something
>> there and only clear *those* pages ?
>
> No need for; since it's copy-on-write, not copy-on-read :) we can just
> check for pages that are zero and not rewrite them with zeros.  That's
   I think it is the right way to improve overcommit without breaking
anything.

> what Peter's patches do, I'll review them right away.
>
> Paolo
>


>


-- 
Best Regards

Wenchao Xia