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Re: [Qemu-devel] [PATCH] migration: use XBZRLE only after bulk stage
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH] migration: use XBZRLE only after bulk stage |
Date: |
Fri, 01 Mar 2013 06:52:28 -0700 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130219 Thunderbird/17.0.3 |
On 03/01/2013 06:31 AM, Peter Lieven wrote:
> at the beginning of migration all pages are marked dirty and
> in the first round a bulk migration of all pages is performed.
>
> currently all these pages are copied to the page cache regardless
> if there are frequently updated or not. this doesn't make sense
> since most of these pages are never transferred again.
>
> this patch changes the XBZRLE transfer to only be used after
> the bulk stage has been completed. that means a page is added
> to the page cache the second time it is transferred and XBZRLE
> can benefit from the third time of transfer.
>
> since the page cache is likely smaller than the number of pages
> its also likely that in the second round the page is missing in the
> cache due to collisions in the bulk phase.
>
> on the other hand a lot of unneccssary mallocs, memdups and frees
s/unneccssary/unnecessary/
> are saved.
>
> Signed-off-by: Peter Lieven <address@hidden>
Do you have any benchmark numbers? At any rate, the explanation seems
sound, so a benchmark should show this.
> ---
> arch_init.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
Reviewed-by: Eric Blake <address@hidden>
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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- [Qemu-devel] [PATCH] migration: use XBZRLE only after bulk stage, Peter Lieven, 2013/03/01
- Re: [Qemu-devel] [PATCH] migration: use XBZRLE only after bulk stage,
Eric Blake <=
- Re: [Qemu-devel] [PATCH] migration: use XBZRLE only after bulk stage, Paolo Bonzini, 2013/03/01
- Re: [Qemu-devel] [PATCH] migration: use XBZRLE only after bulk stage, Peter Lieven, 2013/03/01
- Re: [Qemu-devel] [PATCH] migration: use XBZRLE only after bulk stage, Eric Blake, 2013/03/01
- Re: [Qemu-devel] [PATCH] migration: use XBZRLE only after bulk stage, Peter Lieven, 2013/03/01
- Re: [Qemu-devel] [PATCH] migration: use XBZRLE only after bulk stage, Eric Blake, 2013/03/01
- Re: [Qemu-devel] [PATCH] migration: use XBZRLE only after bulk stage, Peter Lieven, 2013/03/01
- Re: [Qemu-devel] [PATCH] migration: use XBZRLE only after bulk stage, Eric Blake, 2013/03/01
- Re: [Qemu-devel] [PATCH] migration: use XBZRLE only after bulk stage, Peter Lieven, 2013/03/04
- Re: [Qemu-devel] [PATCH] migration: use XBZRLE only after bulk stage, Paolo Bonzini, 2013/03/04
- Re: [Qemu-devel] [PATCH] migration: use XBZRLE only after bulk stage, Peter Lieven, 2013/03/04