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Date: Tue, 13 Nov 2012 18:16:30 +0100
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Subject: Re: [Qemu-devel] Migration ToDo list
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To: Orit Wasserman <owasserm@redhat.com>
Cc: quintela@redhat.com, qemu-devel qemu-devel <qemu-devel@nongnu.org>, Michael Roth <mdroth@linux.vnet.ibm.com>, Isaku Yamahata <yamahata@valinux.co.jp>, benoit.hudzia@sap.com, chegu_vinod@hp.com

Il 13/11/2012 18:09, Orit Wasserman ha scritto:
>> > 
>>> >>   b) do scatter/gather of the pages?
> I would prefer to postpone changing the protocol and start with using iov (writev)
> for sending the pages (still sending header and than the page). Later we can 
> move to scatter/gather I'm not sure of how large the performance gain will be.
>> > 
>> > c) Remove compression of non-zero repetitive pages.
> +1
> we can look of identify the zero pages without calling is_dup_page which looks
> expensive.

Identifying ballooned zero pages is useful, because those cause the
clear_page calls in the kernel even in a guest that has been running for
a while.

But a generic solution doesn't really matter, because is_dup_page and
clear_page shouldn't really be in the profile in practice, except in
microbenchmarks.

Paolo