Re: [Qemu-devel] [PATCH 22/46] Migration parameters: Add qmp/hmp commands for setting/viewing

[Eric Blake]

On 07/04/2014 11:41 AM, Dr. David Alan Gilbert (git) wrote:
> From: "Dr. David Alan Gilbert" <address@hidden>
> 
> Add somewhere for the various migration parameters to be set with
> one command;
> 
> As suggested in the thread:
> http://lists.gnu.org/archive/html/qemu-devel/2012-11/msg00243.html

That's a bit old; I had a newer suggestion here:
https://lists.gnu.org/archive/html/qemu-devel/2014-03/msg02274.html

with positive feedback here and in further followups:
https://lists.gnu.org/archive/html/qemu-devel/2014-04/msg00653.html

> 
> There are many existing migration parameters that are scattered over
> many individual commands; moving those to this scheme would probably break
> things for others, so I've left them be.

I don't mind having information duplicated into two places.  I'd much
rather have all the old commands continue to work one item at a time,
but have the new command (or new extension to existing command) globally
show all tunables, than trying to force management to mix both old and
new calls.  That is, if the new approach works, libvirt would rather use
JUST the new approach instead of a mix of old and new, when managing all
the tunables.

> 
> Preserve the migration tunable values across the reinit of the migration
> status in the same way that the capability flags are preserved.
> 
> Add completion routine for it.
> 
> Use the postcopy time out setting as the first parameter.
> 
> Signed-off-by: Dr. David Alan Gilbert <address@hidden>
> ---
>  hmp-commands.hx               | 17 ++++++++++
>  hmp.c                         | 54 ++++++++++++++++++++++++++++++
>  hmp.h                         |  4 +++
>  include/migration/migration.h |  4 +++
>  migration.c                   | 78 
> ++++++++++++++++++++++++++++++++++---------
>  monitor.c                     | 25 ++++++++++++++
>  qapi-schema.json              | 50 +++++++++++++++++++++++++++
>  qmp-commands.hx               | 23 +++++++++++++
>  8 files changed, 239 insertions(+), 16 deletions(-)
> 

> +++ b/qapi-schema.json
> @@ -538,6 +538,56 @@
>  { 'command': 'query-migrate-capabilities', 'returns':   
> ['MigrationCapabilityStatus']}
>  
>  ##
> +# @MigrationParameterName
> +#
> +# Migration parameter enumeration
> +#     Most existing parameters have separate commands/entries but it seems
> +#     better to group them in the same way as the capability flags
> +#
> +# @x-postcopy-start-time: Time (in ms) after the start of migration to 
> consider
> +#                         switching to postcopy mode
> +#
> +# Since: 2.0

Not even close to 2.0 material.  This is 2.2 at the earliest. (Several
more instances in this patch)

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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