add blkIoTune support for a specific device at vm creation

[Mei Liu]

On 05/26/2013 09:28 PM, Eli Mesika wrote:
>
> ----- Original Message -----
>> From: "Dan Kenigsberg" <danken at redhat.com>
>> To: "Doron Fediuck" <dfediuck at redhat.com>, "Eli Mesika" <emesika at redhat.com>
>> Cc: "Mei Liu" <liumbj at linux.vnet.ibm.com>, arch at ovirt.org
>> Sent: Thursday, May 23, 2013 6:36:42 PM
>> Subject: Re: add blkIoTune support for a specific device at vm creation
>>
>> On Wed, May 22, 2013 at 11:55:26AM -0400, Doron Fediuck wrote:
>>> ----- Original Message -----
>>>> From: "Mei Liu" <liumbj at linux.vnet.ibm.com>
>>>> To: arch at ovirt.org
>>>> Cc: dfediuck at redhat.com, wudxw at linux.vnet.ibm.com
>>>> Sent: Monday, May 20, 2013 6:07:53 AM
>>>> Subject: add blkIoTune support for a specific device at vm creation
>>>>
>>>> Hi all,
>>>> I would like to add blkIoTune support for a specific device at vm
>>>> creation.
>>>>
>>>> The code parses the 'blkIoTune' descrption for block devices at vm
>>>> creation
>>>> time and adds iotune tag accordingly.
>>>>
>>>> e.g.
>>>> Adding 'blkIoTune':{'read_bytes_sec': 6120000, 'total_iops_sec': 800} for
>>>> a
>>>> block device will add the following in dom xml for that device.
>>>>
>>>> <iotune>
>>>>        <read_bytes_sec>6120000</read_bytes_sec>
>>>>        <total_iops_sec>800</total_iops_sec>
>>>> </iotune>
>>>>
>>>> The patch is under review in http://gerrit.ovirt.org/#/c/14636/ .
>>>>
>>>> Does the patch meet the requirement of the engine or the whole
>>>> architecture? Are the new parameters properly placed?  Any suggestions
>>>> are welcomed.
>>>>
>>>> TIA.
>>>>
>>>> Best reagrds,
>>>> Mei Liu (Rose)
>>>>
>>>>
>>> Hi Mei Liu,
>>> Apologies for my late response.
>>> Is there an engine implementation for it?
>>> This is important enough to be considered on how it works in a cluster
>>> on not just on host level. For example, what happens during and after
>>> live migration?
>> As far as I know, there's nothing written on the Engine side, yet.
>>
>> And in my opinion, we can aim low, and have a very minimalistic
>> implementation, that give a thin GUI for each block device, in where
>> these two parameters can be edited, and passed to Vdsm on vmCreate,
>> hotplug, and vmUpdateDevice.
>>
>> Obviously, such an implementation affects only in the vDisk level; the
>> io throttling would follow the VM to the destination node, regardless of
>> other readers/writers on that host. This is suboptimal; it would be
>> cooler to have a policy that provides relative io priority to different
>> vDisks/VMs/users. But in my opinion, it can wait for a second phase.
>>
>> I'm fine with the suggested Engine/Vdsm API (though I'd try to be even
>> more just-like-libvirt and call it "iotune"). But I'm no Engine expert
>> to judge - the may wnat to hide it in their specParam map.
> Right, ant reason why not to use the specParam
> s here ???

No specific reason for doing so. I moved them to specParams.


>
>> I'd love to see a feature page written for this, anyway!
>>
>>
>> Dan.
>>
I have updated the patch in http://gerrit.ovirt.org/#/c/14636/ and put 
these parameters in specParams.
Appreciate that you take a look and give suggestions.