Re: [Qemu-devel] [PATCH v10 08/10] migration: postcopy_blocktime documentation

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Alexey Perevalov (a.perevalov@samsung.com) wrote:
> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> Signed-off-by: Alexey Perevalov <a.perevalov@samsung.com>

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 / dgilbert@redhat.com / Manchester, UK