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From: Tejun Heo <tj@kernel.org>
To: Waiman Long <longman@redhat.com>
Cc: Zefan Li <lizefan.x@bytedance.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Jonathan Corbet <corbet@lwn.net>, Shuah Khan <shuah@kernel.org>,
	linux-kernel@vger.kernel.org, cgroups@vger.kernel.org,
	linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org,
	Juri Lelli <juri.lelli@redhat.com>,
	Valentin Schneider <vschneid@redhat.com>,
	Frederic Weisbecker <frederic@kernel.org>,
	Mrunal Patel <mpatel@redhat.com>,
	Ryan Phillips <rphillips@redhat.com>,
	Brent Rowsell <browsell@redhat.com>,
	Peter Hunt <pehunt@redhat.com>, Phil Auld <pauld@redhat.com>
Subject: Re: [PATCH v4 0/9] cgroup/cpuset: Support remote partitions
Date: Mon, 10 Jul 2023 11:08:30 -1000	[thread overview]
Message-ID: <ZKxzTrN2yiKfXndI@slm.duckdns.org> (raw)
In-Reply-To: <20230627143508.1576882-1-longman@redhat.com>

Hello, Waiman.

I applied the prep patches. They look good on their own.

On Tue, Jun 27, 2023 at 10:34:59AM -0400, Waiman Long wrote:
...
> cpuset. Unlike "cpuset.cpus", invalid input to "cpuset.cpus.exclusive"
> will be rejected with an error. This new control file has no effect on

We cannot maintain this as an invariant tho, right? For example, what
happens when a parent cgroup later wants to withdraw a CPU from its
cpuset.cpus which should always be allowed regardless of what its
descendants are doing? Even with cpus.exclusive itself, I think it'd be
important to always allow ancestors to be able to withdraw from the
commitment as with other resources. I suppose one can argue that giving
exclusive access to CPUs is a special case which doesn't follow this rule
but cpus.exclusive having to be nested inside cpus which is subject to that
rule makes that combination too contorted.

Would it be difficult to follow how isolation modes behave when the target
configuration can't be achieved?

Thanks.

-- 
tejun

  parent reply	other threads:[~2023-07-10 21:08 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-06-27 14:34 [PATCH v4 0/9] cgroup/cpuset: Support remote partitions Waiman Long
2023-06-27 14:35 ` [PATCH v4 1/9] cgroup/cpuset: Inherit parent's load balance state in v2 Waiman Long
2023-06-27 14:35 ` [PATCH v4 2/9] cgroup/cpuset: Extract out CS_CPU_EXCLUSIVE & CS_SCHED_LOAD_BALANCE handling Waiman Long
2023-06-27 14:35 ` [PATCH v4 3/9] cgroup/cpuset: Improve temporary cpumasks handling Waiman Long
     [not found] ` <20230627143508.1576882-1-longman-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2023-06-27 14:35   ` [PATCH v4 4/9] cgroup/cpuset: Allow suppression of sched domain rebuild in update_cpumasks_hier() Waiman Long
2023-07-10 21:01     ` Tejun Heo
2023-06-27 14:35   ` [PATCH v4 8/9] cgroup/cpuset: Documentation update for partition Waiman Long
2023-07-10 21:30     ` Tejun Heo
     [not found]       ` <ZKx4ZJowRhRtjZxB-NiLfg/pYEd1N0TnZuCh8vA@public.gmane.org>
2023-07-11  0:21         ` Waiman Long
2023-07-11  0:42           ` Tejun Heo
2023-07-11  0:53             ` Waiman Long
     [not found]               ` <a429e60a-fc4f-60b0-3978-71596fed9542-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2023-07-11  1:07                 ` Tejun Heo
2023-07-11  3:24                   ` Waiman Long
2023-06-27 14:35 ` [PATCH v4 5/9] cgroup/cpuset: Add cpuset.cpus.exclusive for v2 Waiman Long
2023-06-27 14:35 ` [PATCH v4 6/9] cgroup/cpuset: Introduce remote partition Waiman Long
2023-06-27 14:35 ` [PATCH v4 7/9] cgroup/cpuset: Check partition conflict with housekeeping setup Waiman Long
2023-06-27 14:35 ` [PATCH v4 9/9] cgroup/cpuset: Extend test_cpuset_prs.sh to test remote partition Waiman Long
2023-07-10 21:08 ` Tejun Heo [this message]
2023-07-11  0:33   ` [PATCH v4 0/9] cgroup/cpuset: Support remote partitions Waiman Long
2023-07-11  1:00     ` Tejun Heo
2023-07-11  1:38       ` Waiman Long
2023-07-11  1:45         ` Tejun Heo

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