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Sender: Tejun Heo <htejun@gmail.com>
Date:   Sat, 2 Jul 2022 05:15:43 +0900
From:   Tejun Heo <tj@kernel.org>
To:     Benjamin Segall <bsegall@google.com>
Cc:     Zhang Qiao <zhangqiao22@huawei.com>, mingo@redhat.com,
        peterz@infradead.org, Juri Lelli <juri.lelli@redhat.com>,
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        vschneid@redhat.com, dietmar.eggemann@arm.com, bristot@redhat.com,
        Steven Rostedt <rostedt@goodmis.org>, mgorman@suse.de
Subject: Re: [Question] The system may be stuck if there is a cpu cgroup
 cpu.cfs_quato_us is very low
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On Fri, Jul 01, 2022 at 01:08:21PM -0700, Benjamin Segall wrote:
> Yes, fixing (kernel) priority inversion due to CFS_BANDWIDTH requires a
> serious reworking of how it works, because it would need to dequeue
> tasks individually rather than doing the entire cfs_rq at a time (and
> would require some effort to avoid pinging every throttling task to get
> it into the kernel).

Right, I don't have a good idea on evolving the current implementation
into something correct. As you pointed out, we need to account along
the sched_group tree but conditionally enforce on each thread.

Thanks.

-- 
tejun