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Date: Fri, 09 Aug 2013 17:38:12 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] Are there plans to achieve ram live Snapshot
	feature?
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To: Chijianchun <chijianchun@huawei.com>
Cc: "aliguori@us.ibm.com" <aliguori@us.ibm.com>, "kvm@vger.kernel.org" <kvm@vger.kernel.org>, "mtosatti@redhat.com" <mtosatti@redhat.com>, "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>, "paul@codesourcery.com" <paul@codesourcery.com>, "avi@redhat.com" <avi@redhat.com>

Il 09/08/2013 12:20, Chijianchun ha scritto:
> Now in KVM, when RAM snapshot, vcpus needs stopped, it is Unfriendly
> restrictions to users.  
> 
> Are there plans to achieve ram live Snapshot feature?
> 
> in my mind, Snapshots can not occupy additional too much memory, So when
> the memory needs to be changed, the old memory page is needed to flush
> to the file first.  But flushing to file is too slower than memory,  and
> when flushing, the vcpu or VM is need to be paused until finished
> flushing,  so pause...resume...pause...resume............., more and
> more slower.
> 
> Is this idea feasible? Are there any other thoughts?
> 

This looks very similar to postcopy migration (you can Google it).  The
infrastructure for postcopy migration could be used for this as well.

Paolo