linux-kernel - Re: [PATCH v9 0/8] sched/deadline: fix cpusets bandwidth accounting

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Message-ID: <bbc98035-f960-f06a-66fc-24509ea51a5c@arm.com>
Date:   Wed, 24 Jul 2019 10:45:44 +0200
From:   Dietmar Eggemann <dietmar.eggemann@....com>
To:     Juri Lelli <juri.lelli@...hat.com>, peterz@...radead.org,
        mingo@...hat.com, rostedt@...dmis.org, tj@...nel.org
Cc:     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,
        longman@...hat.com, cgroups@...r.kernel.org
Subject: Re: [PATCH v9 0/8] sched/deadline: fix cpusets bandwidth accounting

On 7/19/19 3:59 PM, Juri Lelli wrote:
> Hi,
> 
> v9 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 the usual rebase on top of cgroup/for-next, this version
> 
>  - make cpuset_{can,cancel}_attach grab cpuset_rwsem for write (5/8 - Peter)
>  - moves v8 8/8 to 7/8 for bisectability (Peter)
>  - adds comment in changelog regarding normalize_rt_tasks() (8/8 - Peter)
> 
> Set also available at
> 
>  https://github.com/jlelli/linux.git fixes/deadline/root-domain-accounting-v9

Tested-by: Dietmar Eggemann <dietmar.eggemann@....com>

Test description:

Juno-r0 (Arm64 big/Little [L b b L L L]) with 6 DL tasks
(12000/100000/100000).

Rt-app runs DL workload for 10min.

After rt-app launched, start CPU hotplug stress test (random CPU hp
in/out except for CPU1 (CPU orig capacity 1024 (big)) during the entire
rt-app run.

Tests ran with 1 and 2 (exclusive cpusets ([0,3-5], [1-2])) root domains.