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>,
cgroups@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org,
"Andrew Morton" <akpm@linux-foundation.org>,
"Roman Gushchin" <guro@fb.com>, "Phil Auld" <pauld@redhat.com>,
"Peter Zijlstra" <peterz@infradead.org>,
"Juri Lelli" <juri.lelli@redhat.com>,
"Frederic Weisbecker" <frederic@kernel.org>,
"Marcelo Tosatti" <mtosatti@redhat.com>,
"Michal Koutný" <mkoutny@suse.com>
Subject: Re: [PATCH v9 2/7] cgroup/cpuset: Allow no-task partition to have empty cpuset.cpus.effective
Date: Mon, 13 Dec 2021 10:45:33 -1000 [thread overview]
Message-ID: <Ybew7d2oE2gLcLNO@slm.duckdns.org> (raw)
In-Reply-To: <20211205183220.818872-3-longman@redhat.com>
On Sun, Dec 05, 2021 at 01:32:15PM -0500, Waiman Long wrote:
> adding = deleting = false;
> old_prs = new_prs = cpuset->partition_root_state;
> if (cmd == partcmd_enable) {
> + /*
> + * Enabling partition root is not allowed if not all the CPUs
> + * can be granted from parent's effective_cpus.
> + */
> + if (!cpumask_subset(cpuset->cpus_allowed, parent->effective_cpus))
> + return -EINVAL;
> +
> + /*
> + * A parent can be left with no CPU as long as there is no
> + * task directly associated with the parent partition. For
> + * such a parent, no new task can be moved into it.
> + */
> + if (partition_is_populated(parent, cpuset) &&
> + cpumask_equal(cpuset->cpus_allowed, parent->effective_cpus))
> + return -EINVAL;
So, given that this only happens with threaded domains, can we just not
allow partitions within threaded domains? The combination doesn't make whole
lot of sense to me anyway.
> + /*
> + * On default hierarchy, task cannot be moved to a cpuset with empty
> + * effective cpus.
> + */
> + if (is_in_v2_mode() && cpumask_empty(cs->effective_cpus))
> + goto out_unlock;
And then we can avoid this extra restriction too, right?
Thanks.
--
tejun
next prev parent reply other threads:[~2021-12-13 20:45 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-05 18:32 [PATCH v9 0/7] cgroup/cpuset: Add new cpuset partition type & empty effecitve cpus Waiman Long
2021-12-05 18:32 ` [PATCH v9 1/7] cgroup/cpuset: Don't let child cpusets restrict parent in default hierarchy Waiman Long
2021-12-13 20:41 ` Tejun Heo
2021-12-15 12:23 ` Michal Koutný
2021-12-15 17:59 ` Waiman Long
2021-12-17 15:48 ` [PATCH] cgroup/cpuset: Make child cpusets restrict parents on v1 hierarchy Michal Koutný
2021-12-17 16:34 ` Waiman Long
2022-01-12 21:25 ` Tejun Heo
2021-12-05 18:32 ` [PATCH v9 2/7] cgroup/cpuset: Allow no-task partition to have empty cpuset.cpus.effective Waiman Long
2021-12-13 20:45 ` Tejun Heo [this message]
2021-12-15 3:24 ` Waiman Long
2021-12-15 10:36 ` Michal Koutný
2021-12-05 18:32 ` [PATCH v9 3/7] cgroup/cpuset: Refining features and constraints of a partition Waiman Long
2021-12-15 14:49 ` Michal Koutný
2021-12-15 16:29 ` Waiman Long
2021-12-16 9:28 ` Michal Koutný
2021-12-05 18:32 ` [PATCH v9 4/7] cgroup/cpuset: Add a new isolated cpus.partition type Waiman Long
2022-01-12 15:21 ` Peter Zijlstra
2022-01-12 15:40 ` Waiman Long
2022-01-12 21:23 ` Tejun Heo
2021-12-05 18:32 ` [PATCH v9 5/7] cgroup/cpuset: Show invalid partition reason string Waiman Long
2021-12-05 18:32 ` [PATCH v9 6/7] cgroup/cpuset: Update description of cpuset.cpus.partition in cgroup-v2.rst Waiman Long
2021-12-13 21:00 ` Tejun Heo
2021-12-15 14:44 ` Michal Koutný
2021-12-15 18:16 ` Waiman Long
2021-12-15 18:35 ` Tejun Heo
2021-12-15 18:55 ` Waiman Long
2022-01-12 21:21 ` Tejun Heo
2021-12-05 18:32 ` [PATCH v9 7/7] kselftest/cgroup: Add cpuset v2 partition root state test Waiman Long
2021-12-09 15:39 ` [PATCH v9 0/7] cgroup/cpuset: Add new cpuset partition type & empty effecitve cpus Waiman Long
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