[libvirt] The design choice for how to enable block I/O throttling function in libvirt

[shu ming]

Zhi Yong Wu:
> On Tue, Aug 30, 2011 at 3:18 PM, shu ming<shuming at linux.vnet.ibm.com>  wrote:
>> See commens below.
>> Zhi Yong Wu:
>>> HI, folks,
>>>
>>> I am trying to enable block I/O throttling function in libvirt. But
>>> currently i met some design questions, and don't make sure if we
>>> should extend blkiotune to support block I/O throttling or introduce
>>> one new libvirt command "blkiothrottle" to cover it or not. If you
>>> have some better idea, pls don't hesitate to drop your comments.
>>>
>>> If one new libvirt command "blkiothrottle" is introduced, I plan to
>>> design its usage syntax as below:
>>>
>>> virsh # help blkiothrottle
>>>    NAME
>>>      blkiothrottle - Set or display a block disk I/O throttle setting.
>>>
>>>    SYNOPSIS
>>>      blkiothrottle<domain>    <device>    [--bps<number>] [--bps_rd
>>> <number>] [--bps_wr<number>] [--iops<number>] [--iops_rd<number>]
>>> [--iops_wr<number>]
>>>
>>>    DESCRIPTION
>>>      Set or display a block disk I/O throttle setting.
>>>
>>>    OPTIONS
>>>      [--domain]<string>     domain name, id or uuid
>>>      [--device]<string>     block device
>>>      --bps<number>      total throughput limits in bytes/s
>>>      --bps_rd<number>     read throughput limits in bytes/s
>>>      --bps_wr<number>     write throughput limits in bytes/s
>>>      --iops<number>     total operation limits in numbers/s
>>>      --iops_rd<number>     read operation limits in numbers/s
>>>      --iops_wr<number>     write operation limits in numbers/s
>>>
>> How to display the current I/O throttle setting of a specific block device
>> here?
> It will show as below:
> virtio0: bps=xxx, bps_rd=xxx, bps_wr=xxx, iops=xxx, iops_rd=xxx, iops_wr=xxx.

With which options to the command?  I guess "blkiothrottle <domain> 
<device>" will display the current setting.