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From: Juan Quintela <quintela@redhat.com>
In-Reply-To: <56374F11.30309@redhat.com> (Paolo Bonzini's message of "Mon, 2
	Nov 2015 12:54:57 +0100")
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Date: Tue, 03 Nov 2015 13:36:28 +0100
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Subject: Re: [Qemu-devel] [v2 RESEND 0/4] Fix long vm downtime during live
	migration
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Wanpeng Li <wanpeng.li@linux.intel.com>, Liang Li <liang.z.li@intel.com>, qemu-devel@nongnu.org, yong.y.wang@intel.com, stefanha@redhat.com, amit.shah@redhat.com

Paolo Bonzini <pbonzini@redhat.com> wrote:
> On 02/11/2015 08:36, Liang Li wrote:
>> The patch 3ea3b7fa9af067982f34b of kvm introduces a lazy collapsing
>> of small sptes into large sptes mechanism, which intend to solve the
>> performance drop issue if live migration fails or is canceled. The
>> rmap will be scanned in the KVM_SET_USER_MEMORY_REGION ioctl context
>> when dirty logging is stopped so as to drop the small sptes, scanning
>> the rmap and drop the small sptes is a time consuming operation which
>> will take dozens of milliseconds, the actual time depends on VM's
>> memory size. For a VM with 8GB RAM, it will take about 30ms.
>
> I'm okay with these patches.  Juan, can they be included in 2.5?

Applied, thanks.

>
> However, the KVM patch is a regression too.  Wanpeng, can you look into
> doing the collapsing from a work item?
>
> Thanks,
>
> Paolo