Re: [Qemu-devel] [PATCH v12 6/6] migration: add postcopy total blocktime into query-migrate

[Eric Blake]

On 10/30/2017 08:16 AM, Alexey Perevalov wrote:
> Postcopy total blocktime is available on destination side only.
> But query-migrate was possible only for source. This patch
> adds ability to call query-migrate on destination.
> To be able to see postcopy blocktime, need to request postcopy-blocktime
> capability.

Why not display the stats unconditionally when they are available,
instead of having to set a capability knob to request them?

> 
> The query-migrate command will show following sample result:
> {"return":
>     "postcopy-vcpu-blocktime": [115, 100],
>     "status": "completed",
>     "postcopy-blocktime": 100
> }}
> 
> postcopy_vcpu_blocktime contains list, where the first item is the first
> vCPU in QEMU.
> 
> This patch has a drawback, it combines states of incoming and
> outgoing migration. Ongoing migration state will overwrite incoming
> state. Looks like better to separate query-migrate for incoming and
> outgoing migration or add parameter to indicate type of migration.
> 
> Reviewed-by: Dr. David Alan Gilbert <address@hidden>
> Signed-off-by: Alexey Perevalov <address@hidden>
> ---

> +++ b/qapi/migration.json
> @@ -156,6 +156,13 @@
>  #              @status is 'failed'. Clients should not attempt to parse the
>  #              error strings. (Since 2.7)
>  #
> +# @postcopy-blocktime: total time when all vCPU were blocked during postcopy
> +#           live migration (Since 2.11)

2.12 now.

Should this mention the capability knob needed to enable this stat (or
else get rid of the capability knob and always expose this when possible)?

> +#
> +# @postcopy-vcpu-blocktime: list of the postcopy blocktime per vCPU (Since 
> 2.11)

Also 2.12.

> +#
> +
> +#
>  # Since: 0.14.0
>  ##
>  { 'struct': 'MigrationInfo',
> @@ -167,7 +174,9 @@
>             '*downtime': 'int',
>             '*setup-time': 'int',
>             '*cpu-throttle-percentage': 'int',
> -           '*error-desc': 'str'} }
> +           '*error-desc': 'str',
> +           '*postcopy-blocktime' : 'int64',
> +           '*postcopy-vcpu-blocktime': ['int64']} }
>  
>  ##
>  # @query-migrate:
> 

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

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