From: Peter Zijlstra <peterz@infradead.org>
To: Waiman Long <longman@redhat.com>
Cc: "Andrea Righi" <arighi@nvidia.com>,
"Michal Koutný" <mkoutny@suse.com>, "Tejun Heo" <tj@kernel.org>,
"David Vernet" <void@manifault.com>,
"Changwoo Min" <changwoo@igalia.com>,
"Ridong Chen" <ridong.chen@linux.dev>,
"Johannes Weiner" <hannes@cmpxchg.org>,
sched-ext@lists.linux.dev, cgroups@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/3] cgroup/cpuset: Protect is_in_v2_mode() in cpuset_num_cpus()
Date: Wed, 30 Sep 2026 10:11:25 +0200 [thread overview]
Message-ID: <20260930081125.GF88198@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <500cb19a-549b-4055-a807-c3c40da787ae@redhat.com>
On Tue, Sep 29, 2026 at 03:46:23PM -0400, Waiman Long wrote:
> The cpuset_v2_mode mount option is only for making the cpuset.cpus and
> cpuset.mems behave like in v2. The cpu-cgroup and cpuset-cgroup can still be
> in separate hierarchies. If cross-cgroup transition is the main point, it
> won't work with the cpuset_v2_mode mount option. We should switch to use
> cpuset_v2().
Yes, the cross-cgroup transition is fundamental to how this works.
Without that you cannot reasonably talk about the CPUs of a cpu-cgroup,
you need to have cpu and cpuset aligned.
next prev parent reply other threads:[~2026-09-30 8:11 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-29 8:37 [PATCHSET sched_ext/for-7.4] sched_ext: Add scx_bpf_cgroup_nr_cpus() Andrea Righi
2026-09-29 8:37 ` [PATCH 1/3] cgroup/cpuset: Protect is_in_v2_mode() in cpuset_num_cpus() Andrea Righi
2026-09-29 13:47 ` Michal Koutný
2026-09-29 15:32 ` Waiman Long
2026-09-29 17:35 ` Andrea Righi
2026-09-29 18:10 ` Waiman Long
2026-09-29 19:08 ` Peter Zijlstra
2026-09-29 19:46 ` Waiman Long
2026-09-30 8:11 ` Peter Zijlstra [this message]
2026-09-29 19:57 ` Andrea Righi
2026-09-29 8:37 ` [PATCH 2/3] sched_ext: Introduce scx_bpf_cgroup_nr_cpus() Andrea Righi
2026-09-29 8:37 ` [PATCH 3/3] selftests/sched_ext: Test scx_bpf_cgroup_nr_cpus() Andrea Righi
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