From: "Michal Koutný" <mkoutny@suse.com>
To: Waiman Long <longman@redhat.com>
Cc: Tejun Heo <tj@kernel.org>, 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>
Subject: Re: [RFC PATCH 0/5] cgroup/cpuset: A new "isolcpus" paritition
Date: Wed, 3 May 2023 00:27:24 +0200 [thread overview]
Message-ID: <ZFGOTHQj3k5rzmyR@blackbook> (raw)
In-Reply-To: <f2bd7b1e-190e-1d08-f085-b4cae36fb5be@redhat.com>
On Tue, May 02, 2023 at 05:26:17PM -0400, Waiman Long <longman@redhat.com> wrote:
> In the new scheme, the available cpus are still directly passed down to a
> descendant cgroup. However, isolated CPUs (or more generally CPUs dedicated
> to a partition) have to be exclusive. So what the cpuset.cpus.reserve does
> is to identify those exclusive CPUs that can be excluded from the
> effective_cpus of the parent cgroups before they are claimed by a child
> partition. Currently this is done automatically when a child partition is
> created off a parent partition root. The new scheme will break it into 2
> separate steps without the requirement that the parent of a partition has to
> be a partition root itself.
new scheme
1st step:
echo C >p/cpuset.cpus.reserve
# p/cpuset.cpus.effective == A-C (1)
2nd step (claim):
echo C' >p/c/cpuset.cpus # C'⊆C
echo root >p/c/cpuset.cpus.partition
current scheme
1st step (configure):
echo C >p/c/cpuset.cpus
2nd step (reserve & claim):
echo root >p/c/cpuset.cpus.partition
# p/cpuset.cpus.effective == A-C (2)
As long as p/c is unpopulated, (1) and (2) are equal situations.
Why is the (different) two step procedure needed?
Also the relaxation of requirement of a parent being a partition
confuses me -- if the parent is not a partition, i.e. it has no
exclusive ownership of CPUs but it can still "give" it to children -- is
child partition meant to be exclusive? (IOW can parent siblings reserve
some same CPUs?)
Thanks,
Michal
next prev parent reply other threads:[~2023-05-02 22:27 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-12 15:37 [RFC PATCH 0/5] cgroup/cpuset: A new "isolcpus" paritition Waiman Long
2023-04-12 19:28 ` Tejun Heo
[not found] ` <1ce6a073-e573-0c32-c3d8-f67f3d389a28@redhat.com>
2023-04-12 20:22 ` Tejun Heo
2023-04-12 20:33 ` Waiman Long
2023-04-13 0:03 ` Tejun Heo
2023-04-13 0:26 ` Waiman Long
2023-04-13 0:33 ` Tejun Heo
2023-04-13 0:55 ` Waiman Long
2023-04-13 1:17 ` Tejun Heo
2023-04-13 1:55 ` Waiman Long
2023-04-14 1:22 ` Waiman Long
2023-04-14 16:54 ` Tejun Heo
2023-04-14 17:29 ` Waiman Long
2023-04-14 17:34 ` Tejun Heo
2023-04-14 17:38 ` Waiman Long
2023-04-14 19:06 ` Waiman Long
2023-05-02 18:01 ` Michal Koutný
2023-05-02 21:26 ` Waiman Long
2023-05-02 22:27 ` Michal Koutný [this message]
2023-05-04 3:01 ` Waiman Long
2023-05-05 16:03 ` Tejun Heo
2023-05-05 16:25 ` Waiman Long
2023-05-08 1:03 ` Waiman Long
2023-05-22 19:49 ` Tejun Heo
2023-05-28 21:18 ` Waiman Long
2023-06-05 18:03 ` Tejun Heo
2023-06-05 20:00 ` Waiman Long
2023-06-05 20:27 ` Tejun Heo
2023-06-06 2:47 ` Waiman Long
2023-06-06 19:58 ` Tejun Heo
2023-06-06 20:11 ` Waiman Long
2023-06-06 20:13 ` Tejun Heo
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