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Re: [Qemu-devel] [RFC PATCH v2] Throttle-down guest when live migration
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [RFC PATCH v2] Throttle-down guest when live migration does not converge. |
Date: |
Mon, 29 Apr 2013 08:53:45 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130402 Thunderbird/17.0.5 |
On 04/27/2013 02:50 PM, Chegu Vinod wrote:
> Busy enterprise workloads hosted on large sized VM's tend to dirty
> memory faster than the transfer rate achieved via live guest migration.
> Despite some good recent improvements (& using dedicated 10Gig NICs
> between hosts) the live migration does NOT converge.
>
>
> No exernal trigger is required (unlike option 1) and it can co-exist
s/exernal/external/
> with enhancements being pursued as part of Option 2 (e.g. RDMA).
>
> Thanks to Juan and Paolo for their useful suggestions.
>
>
> ---
>
> (qemu) info migrate
> capabilities: xbzrle: off auto-converge: on <----
This part looks nice.
I'm not reviewing the entire patch (I'm not an expert on the internals
of migration), but just the interface:
> +++ b/qapi-schema.json
> @@ -599,10 +599,14 @@
> # This feature allows us to minimize migration traffic for certain
> work
> # loads, by sending compressed difference of the pages
> #
> +# @auto-converge: Controls whether or not the we want the migration to
> +# automaticially detect and force convergence by slowing
s/automaticially/automatically/
> +# down the guest. Disabled by default.
Missing a (since 1.6) designation.
Also, use of first-person (us, we) in docs seems a bit unprofessional,
although you were copying pre-existing usage. How about:
@xbzrle: Migration supports xbzrle (Xor Based Zero Run Length Encoding),
which minimizes migration traffic for certain workloads by
sending compressed differences of active pages
@auto-converge: Migration supports automatic throttling of guest
activity to force convergence (since 1.6)
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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