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Re: [Qemu-devel] [PATCH v10 08/10] migration: postcopy_blocktime documen
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [PATCH v10 08/10] migration: postcopy_blocktime documentation |
Date: |
Thu, 21 Sep 2017 13:33:27 +0100 |
User-agent: |
Mutt/1.8.3 (2017-05-23) |
* Alexey Perevalov (address@hidden) wrote:
> Reviewed-by: Dr. David Alan Gilbert <address@hidden>
> Signed-off-by: Alexey Perevalov <address@hidden>
Although it does have my R-b it might be worth adding some clarification
that it's a measure of when *all* cpus are blocked and so isn't a
total measure of impact of postcopy (when blocking some of them).
Dave
> ---
> docs/devel/migration.txt | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/docs/devel/migration.txt b/docs/devel/migration.txt
> index 1b940a8..4b625ca 100644
> --- a/docs/devel/migration.txt
> +++ b/docs/devel/migration.txt
> @@ -402,6 +402,16 @@ will now cause the transition from precopy to postcopy.
> It can be issued immediately after migration is started or any
> time later on. Issuing it after the end of a migration is harmless.
>
> +Blocktime is a postcopy live migration metric, intended to show
> +how long the vCPU was in state of interruptable sleep due to pagefault.
> +This value is calculated on destination side.
> +To enable postcopy blocktime calculation, enter following command on
> destination
> +monitor:
> +
> +migrate_set_capability postcopy-blocktime on
> +
> +Postcopy blocktime can be retrieved by query-migrate qmp command.
> +
> Note: During the postcopy phase, the bandwidth limits set using
> migrate_set_speed is ignored (to avoid delaying requested pages that
> the destination is waiting for).
> --
> 1.9.1
>
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
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