Re: [Qemu-devel] [PATCH 7/9] throttle: Add throttle group support

[Eric Blake]

On 02/13/2015 09:06 AM, Alberto Garcia wrote:
> The throttle group support use a cooperative round robin scheduling algorithm.
> 
> The principles of the algorithm are simple:
> - Each BDS of the group is used as a token in a circular way.
> - The active BDS compute if a wait must be done and arm the right timer.
> - If a wait must be done the token timer will be armed so the token will 
> become
>   the next active BDS.
> 
> Signed-off-by: Alberto Garcia <address@hidden>
> ---
>  block.c                   | 212 
> +++++++++++++++++++++++++++++++++++++++-------
>  block/qapi.c              |   7 +-
>  block/throttle-groups.c   |   2 +-
>  blockdev.c                |  19 ++++-
>  hmp.c                     |   4 +-
>  include/block/block.h     |   3 +-
>  include/block/block_int.h |   9 +-
>  qapi/block-core.json      |   5 +-
>  qemu-options.hx           |   1 +
>  qmp-commands.hx           |   3 +-

Just a qapi review for now...


> +++ b/qapi/block-core.json
> @@ -989,6 +989,9 @@
>  #
>  # @iops_size: #optional an I/O size in bytes (Since 1.7)
>  #
> +#

Why the extra blank line?

> +# @group: #optional throttle group name (Since 2.3)
> +#
>  # Returns: Nothing on success
>  #          If @device is not a valid block device, DeviceNotFound
>  #
> @@ -1000,7 +1003,7 @@
>              '*bps_max': 'int', '*bps_rd_max': 'int',
>              '*bps_wr_max': 'int', '*iops_max': 'int',
>              '*iops_rd_max': 'int', '*iops_wr_max': 'int',
> -            '*iops_size': 'int' } }
> +            '*iops_size': 'int', '*group': 'str' } }

What is the default if no 'group' is specified, unthrottled?

I hate write-only interfaces.  What is the corresponding 'query-*'
command that I can invoke to learn which group, if any, a node is
associated with?

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

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