Re: [RFC 01/16] blkcg:Introduce blkio.app_identifier knob to blkio controller

Hannes Reinecke
2020-08-05T06:33:24Z

On 8/5/20 5:59 AM, Ming Lei wrote:
> On Wed, Aug 5, 2020 at 8:42 AM James Smart <james.smart@broadcom.com> wrote:
>>
>> On 8/4/2020 7:21 AM, Tejun Heo wrote:
>>> Hello,
>>>
>>> On Tue, Aug 04, 2020 at 01:31:30PM +0200, Daniel Wagner wrote:
>>>> Hi,
>>>>
>>>> [cc Tejun]
>>>>
>>>> On Tue, Aug 04, 2020 at 07:43:01AM +0530, Muneendra wrote:
>>>>> This Patch added a unique application identifier i.e
>>>>> blkio.app_identifier knob to blkio controller which
>>>>> allows identification of traffic sources at an
>>>>> individual cgroup based Applications
>>>>> (ex:virtual machine (VM))level in both host and
>>>>> fabric infrastructure.
>>> I'm not sure it makes sense to introduce custom IDs for these given that
>>> there already are unique per-host cgroup IDs which aren't recycled.
>>>
>>> Thanks.
>>>
>>
>> If the VM moves to a different host, does the per-host cgroup IDs
>> migrate with the VM ? If not, we need to have an identifier that moves
>> with the VM and which is independent of what host the VM is residing on.
>
> Hello James,
>
> Is it possible to reuse VM's mac address or other unique ID for such purpose?
>
None of these are guaranteed to be either present or unique.
It's not uncommon to have VMs with more than one MAC address, and any
other unique identifier like system UUID is not required to be present.

Cheers,

Hannes
--
Dr. Hannes Reinecke Teamlead Storage & Networking
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