linux-kernel - Re: [PATCH v6 0/5] sched/deadline: fix cpusets bandwidth accounting

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Message-ID: <90ece065-8634-7a6c-7852-e04f6d727a13@redhat.com>
Date:   Mon, 4 Feb 2019 13:45:03 -0500
From:   Waiman Long <longman@...hat.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Juri Lelli <juri.lelli@...hat.com>
Cc:     mingo@...hat.com, rostedt@...dmis.org,
        linux-kernel@...r.kernel.org, luca.abeni@...tannapisa.it,
        claudio@...dence.eu.com, tommaso.cucinotta@...tannapisa.it,
        bristot@...hat.com, mathieu.poirier@...aro.org, lizefan@...wei.com,
        cgroups@...r.kernel.org, tj@...nel.org
Subject: Re: [PATCH v6 0/5] sched/deadline: fix cpusets bandwidth accounting

On 02/04/2019 07:18 AM, Peter Zijlstra wrote:
> On Mon, Feb 04, 2019 at 10:02:11AM +0100, Juri Lelli wrote:
>> On 18/01/19 17:46, Juri Lelli wrote:
>>> On 18/01/19 08:17, Tejun Heo wrote:
>>>> On Thu, Jan 17, 2019 at 09:47:34AM +0100, Juri Lelli wrote:
>>>>> Hi,
>>>>>
>>>>> v6 of a series of patches, originally authored by Mathieu, with the intent
>>>>> of fixing a long standing issue of SCHED_DEADLINE bandwidth accounting.
>>>>> As originally reported by Steve [1], when hotplug and/or (certain)
>>>>> cpuset reconfiguration operations take place, DEADLINE bandwidth
>>>>> accounting information is lost since root domains are destroyed and
>>>>> recreated.
>>>>>
>>>>> Mathieu's approach is based on restoring bandwidth accounting info on
>>>>> the newly created root domains by iterating through the (DEADLINE) tasks
>>>>> belonging to the configured cpuset(s).
>>>>>
>>>>> Apart from some minor refactoring needed to rebase the set on top of
>>>>> Waiman Long's cpuset for cgroup series (now mainline), two changes worth
>>>>> of notice:
>>>> Generally looks good to me but can you please ask Waiman to take a
>>>> look?
>>> Argh! I should have cc-ed him in the first instance.
>>>
>>> Thanks for reviewing.
>>>
>>> Waiman, do you see anything wrong with this series? Thanks!
>>>
>>> https://lore.kernel.org/lkml/20190117084739.17078-1-juri.lelli@redhat.com/
>> Ping?
> Basically looks OK to me; wlthough I think I prefer the callback_lock /
> rq->lock ordering to be the other way around.
>
> Waiman, you OK with this one?

Sorry for the late reply. I reviewed the patchset and don't see anything
wrong with it. However, my knowledge of the internal operation of the
deadline scheduler is limited.

Cheers,
Longman