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From: "Michal Koutný" <mkoutny@suse.com>
To: Tejun Heo <tj@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
	joel@joelfernandes.org, chris.hyser@oracle.com,
	joshdon@google.com, mingo@kernel.org, vincent.guittot@linaro.org,
	valentin.schneider@arm.com, mgorman@suse.de,
	linux-kernel@vger.kernel.org, tglx@linutronix.de,
	Christian Brauner <christian.brauner@ubuntu.com>,
	Zefan Li <lizefan.x@bytedance.com>
Subject: Re: [PATCH 0/9] sched: Core scheduling interfaces
Date: Wed, 7 Apr 2021 18:50:32 +0200	[thread overview]
Message-ID: <YG3i2JF2vBY4CseK@blackbook> (raw)
In-Reply-To: <YGpOF6f0YcMkWy1u@mtj.duckdns.org>

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Hello.

IIUC, the premise is that the tasks that have different cookies imply
they would never share a core.

On Thu, Apr 01, 2021 at 03:10:12PM +0200, Peter Zijlstra wrote:
> The cgroup interface now uses a 'core_sched' file, which still takes 0,1. It is
> however changed such that you can have nested tags. The for any given task, the
> first parent with a cookie is the effective one. The rationale is that this way
> you can delegate subtrees and still allow them some control over grouping.

Given the existence of prctl and clone APIs, I don't see the reason to
have a separate cgroup-bound interface too (as argued by Tejun). The
potential speciality is the possibility to re-tag whole groups of
processes at runtime (but the listed use cases [1] don't require that
and it's not such a good idea given its asynchronicity).

Also, I would find useful some more explanation how the hierarchical
behavior is supposed to work. In my understanding the task is either
allowed to request its own isolation or not. The cgroups could be used
to restrict this privilege, however, that doesn't seem to be the case
here.

My two cents,
Michal

[1] https://lore.kernel.org/lkml/20200822030155.GA414063@google.com/

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  parent reply	other threads:[~2021-04-07 16:50 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-01 13:10 Peter Zijlstra
2021-04-01 13:10 ` [PATCH 1/9] sched: Allow sched_core_put() from atomic context Peter Zijlstra
2021-04-01 13:10 ` [PATCH 2/9] sched: Implement core-sched assertions Peter Zijlstra
2021-04-01 13:10 ` [PATCH 3/9] sched: Trivial core scheduling cookie management Peter Zijlstra
2021-04-01 20:04   ` Josh Don
2021-04-02  7:13     ` Peter Zijlstra
2021-04-01 13:10 ` [PATCH 4/9] sched: Default core-sched policy Peter Zijlstra
2021-04-21 13:33   ` Peter Zijlstra
2021-04-21 14:31     ` Chris Hyser
2021-04-01 13:10 ` [PATCH 5/9] sched: prctl() core-scheduling interface Peter Zijlstra
2021-04-07 17:00   ` Peter Zijlstra
2021-04-18  3:52     ` Joel Fernandes
2021-04-01 13:10 ` [PATCH 6/9] kselftest: Add test for core sched prctl interface Peter Zijlstra
2021-04-01 13:10 ` [PATCH 7/9] sched: Cgroup core-scheduling interface Peter Zijlstra
2021-04-02  0:34   ` Josh Don
2021-04-01 13:10 ` [PATCH 8/9] rbtree: Remove const from the rb_find_add() comparator Peter Zijlstra
2021-04-01 13:10 ` [PATCH 9/9] sched: prctl() and cgroup interaction Peter Zijlstra
2021-04-03  1:30   ` Josh Don
2021-04-06 15:12     ` Peter Zijlstra
2021-04-04 23:39 ` [PATCH 0/9] sched: Core scheduling interfaces Tejun Heo
2021-04-05 18:46   ` Joel Fernandes
2021-04-06 14:16     ` Tejun Heo
2021-04-18  1:35       ` Joel Fernandes
2021-04-19  9:00         ` Peter Zijlstra
2021-04-21 13:35           ` Peter Zijlstra
2021-04-21 14:45             ` Chris Hyser
2021-04-06 15:32   ` Peter Zijlstra
2021-04-06 16:08     ` Tejun Heo
2021-04-07 18:39       ` Peter Zijlstra
2021-04-07 16:50   ` Michal Koutný [this message]
2021-04-07 18:34     ` Peter Zijlstra
2021-04-08 13:25       ` Michal Koutný
2021-04-08 15:02         ` Peter Zijlstra
2021-04-09  0:16           ` Josh Don
2021-04-19 11:30       ` Tejun Heo
2021-04-20  1:17         ` Josh Don

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