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From: Waiman Long <longman@redhat.com>
To: Tejun Heo <tj@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	cgroups@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-doc@vger.kernel.org, kernel-team@fb.com, pjt@google.com,
	luto@amacapital.net, efault@gmx.de,
	torvalds@linux-foundation.org, Roman Gushchin <guro@fb.com>
Subject: Re: [PATCH v5 2/2] cpuset: Add cpuset.flags control knob to v2
Date: Tue, 20 Mar 2018 16:12:25 -0400	[thread overview]
Message-ID: <cbe9b852-80b6-8341-b51c-4d754d00ce53@redhat.com> (raw)
In-Reply-To: <8e553b7e-cab6-1b5d-9110-cc5770ae16c4@redhat.com>

On 03/19/2018 12:33 PM, Waiman Long wrote:
> On 03/19/2018 12:26 PM, Tejun Heo wrote:
>> Hello, Waiman.
>>
>> On Thu, Mar 15, 2018 at 05:20:42PM -0400, Waiman Long wrote:
>>> +	The currently supported flag is:
>>> +
>>> +	  sched_load_balance
>>> +		When it is not set, there will be no load balancing
>>> +		among CPUs on this cpuset.  Tasks will stay in the
>>> +		CPUs they are running on and will not be moved to
>>> +		other CPUs.
>>> +
>>> +		When it is set, tasks within this cpuset will be
>>> +		load-balanced by the kernel scheduler.  Tasks will be
>>> +		moved from CPUs with high load to other CPUs within
>>> +		the same cpuset with less load periodically.
>> Hmm... looks like this is something which can be decided by the cgroup
>> itself and should be made delegatable.  Given that different flags
>> might need different delegation settings and the precedence of
>> memory.oom_group, I think it'd be better to make the flags separate
>> bool files - ie. cpuset.sched_load_balance which contains 0/1 and
>> marked delegatable.
>>
>> Thanks.
>>
> Sure. Will do that.

After some thought, I am planning to impose the following additional
constraints on how sched_load_balance works in v2.

1) sched_load_balance will be made hierarchical, the child will inherit
the flag from its parent.
2) cpu_exclusive will be implicitly associated with sched_load_balance.
IOW, sched_load_balance => !cpu_exclusive, and !sched_load_balance =>
cpu_exclusive.
3) sched_load_balance cannot be 1 on a child if it is 0 on the parent.

With these changes, sched_load_balance will have to be set by the parent
and so will not be delegatable. Please let me know your thought on that.

Cheers,
Longman

  reply	other threads:[~2018-03-20 20:12 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-15 21:20 [PATCH v5 0/2] cpuset: Enable cpuset controller in default hierarchy Waiman Long
2018-03-15 21:20 ` [PATCH v5 1/2] " Waiman Long
2018-03-19 15:59   ` Tejun Heo
2018-03-20 13:51     ` Waiman Long
2018-03-20 20:10       ` Tejun Heo
2018-03-20 20:53         ` Waiman Long
2018-03-20 21:14           ` Tejun Heo
2018-03-20 22:01             ` Waiman Long
2018-03-15 21:20 ` [PATCH v5 2/2] cpuset: Add cpuset.flags control knob to v2 Waiman Long
2018-03-19 16:26   ` Tejun Heo
2018-03-19 16:33     ` Waiman Long
2018-03-20 20:12       ` Waiman Long [this message]
2018-03-20 20:22         ` Tejun Heo
2018-03-20 20:43           ` Waiman Long

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