From: Tejun Heo <tj@kernel.org>
To: Waiman Long <longman@redhat.com>
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, Mike Galbraith <efault@gmx.de>,
torvalds@linux-foundation.org, Roman Gushchin <guro@fb.com>,
Juri Lelli <juri.lelli@redhat.com>,
Patrick Bellasi <patrick.bellasi@arm.com>
Subject: Re: [PATCH v11 7/9] cpuset: Expose cpus.effective and mems.effective on cgroup v2 root
Date: Mon, 2 Jul 2018 09:53:22 -0700 [thread overview]
Message-ID: <20180702165322.GI533219@devbig577.frc2.facebook.com> (raw)
In-Reply-To: <1529825440-9574-8-git-send-email-longman@redhat.com>
Hello, Waiman.
On Sun, Jun 24, 2018 at 03:30:38PM +0800, Waiman Long wrote:
> Because of the fact that setting the "cpuset.sched.partition" in
> a direct child of root can remove CPUs from the root's effective CPU
> list, it makes sense to know what CPUs are left in the root cgroup for
> scheduling purpose. So the "cpuset.cpus.effective" control file is now
> exposed in the v2 cgroup root.
So, effective changing when enabling partition on a child feels wrong
to me. It's supposed to contain what's actually allowed to the cgroup
from its parent and that shouldn't change regardless of how those
resources are used. It's still given to the cgroup from its parent.
It's a bit different because the way partition behaves is different
from other resource konbs in that it locks away those cpus so that
they can't be taken back.
What do people think about restricting partition to the first level
children for now at least? That way we aren't locked into the special
semantics and we can figure out how to this down the hierarchy later.
Given that we ignore the regular cpuset settings when the set goes
empty (which also is a special condition which only exists for cpuset)
and inherits the parent's, I think the consistent thing to do is doing
the same for partition - if it can't be satisfied, ignore it, but
maybe there is a better way.
Thanks.
--
tejun
next prev parent reply other threads:[~2018-07-02 16:53 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-24 7:30 [PATCH v11 0/9] cpuset: Enable cpuset controller in default hierarchy Waiman Long
2018-06-24 7:30 ` [PATCH v11 1/9] " Waiman Long
2018-06-24 7:30 ` [PATCH v11 2/9] cpuset: Add new v2 cpuset.sched.partition flag Waiman Long
2018-06-24 7:30 ` [PATCH v11 3/9] cpuset: Simulate auto-off of sched.partition at cgroup removal Waiman Long
2018-06-24 7:30 ` [PATCH v11 4/9] cpuset: Allow changes to cpus in a partition root Waiman Long
2018-06-24 7:30 ` [PATCH v11 5/9] cpuset: Make sure that partition flag work properly with CPU hotplug Waiman Long
2018-06-24 7:30 ` [PATCH v11 6/9] cpuset: Make generate_sched_domains() recognize reserved_cpus Waiman Long
2018-06-24 7:30 ` [PATCH v11 7/9] cpuset: Expose cpus.effective and mems.effective on cgroup v2 root Waiman Long
2018-07-02 16:53 ` Tejun Heo [this message]
2018-07-03 0:41 ` Waiman Long
2018-07-03 15:58 ` Tejun Heo
2018-07-06 20:32 ` Waiman Long
2018-07-10 15:23 ` Waiman Long
2018-07-18 15:21 ` Waiman Long
2018-07-18 15:31 ` Tejun Heo
2018-07-18 21:12 ` Waiman Long
2018-07-19 13:52 ` Peter Zijlstra
2018-07-19 14:04 ` Waiman Long
2018-07-19 15:30 ` Tejun Heo
2018-07-19 15:52 ` Waiman Long
2018-07-19 16:52 ` Tejun Heo
2018-07-19 17:22 ` Waiman Long
2018-07-19 17:25 ` Tejun Heo
2018-07-19 17:38 ` Waiman Long
2018-07-20 11:32 ` Peter Zijlstra
2018-07-20 11:31 ` Peter Zijlstra
2018-07-20 11:45 ` Tejun Heo
2018-07-20 12:04 ` Tejun Heo
2018-07-20 15:44 ` Peter Zijlstra
2018-07-20 15:56 ` Tejun Heo
2018-07-20 16:19 ` Waiman Long
2018-07-20 16:37 ` Peter Zijlstra
2018-07-20 17:09 ` Waiman Long
2018-07-20 17:41 ` Tejun Heo
2018-08-13 17:56 ` Waiman Long
2018-08-17 15:59 ` Tejun Heo
2018-08-18 1:03 ` Waiman Long
2018-07-27 21:21 ` Waiman Long
2018-07-20 16:25 ` Peter Zijlstra
2018-07-20 15:57 ` Waiman Long
2018-07-20 11:29 ` Peter Zijlstra
2018-06-24 7:30 ` [PATCH v11 8/9] cpuset: Don't rebuild sched domains if cpu changes in non-partition root Waiman Long
2018-06-24 7:30 ` [PATCH v11 9/9] cpuset: Allow reporting of sched domain generation info Waiman Long
2018-07-19 13:54 ` Peter Zijlstra
2018-07-19 13:56 ` Waiman Long
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