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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>,
	cgroups@vger.kernel.org, linux-kernel@vger.kernel.org,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Subject: Re: [PATCH 2/2] cgroup/cpuset: Optimize cpuset_attach() on v2
Date: Mon, 21 Nov 2022 19:50:42 +0100	[thread overview]
Message-ID: <20221121185042.GA15225@blackbody.suse.cz> (raw)
In-Reply-To: <20221112221939.1272764-3-longman@redhat.com>

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On Sat, Nov 12, 2022 at 05:19:39PM -0500, Waiman Long <longman@redhat.com> wrote:
> +	/*
> +	 * In the default hierarchy, enabling cpuset in the child cgroups
> +	 * will trigger a number of cpuset_attach() calls with no change
> +	 * in effective cpus and mems. In that case, we can optimize out
> +	 * by skipping the task iteration and update.
> +	 */
> +	if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys) &&
> +	    !cpus_updated && !mems_updated) {

I'm just wondering -- why is this limited to the default hierarchy only?
IOW why can't v1 skip too (when favorable constness between cpusets).

Thanks,
Michal

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  reply	other threads:[~2022-11-21 18:50 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-12 22:19 [PATCH 0/2] cgroup/cpuset: v2 optimization Waiman Long
2022-11-12 22:19 ` [PATCH 1/2] cgroup/cpuset: Skip spread flags update on v2 Waiman Long
2022-11-12 22:19 ` [PATCH 2/2] cgroup/cpuset: Optimize cpuset_attach() " Waiman Long
2022-11-21 18:50   ` Michal Koutný [this message]
2022-11-21 19:11     ` Waiman Long
2022-11-23 15:19   ` Sebastian Andrzej Siewior
2022-11-14 21:46 ` [PATCH 0/2] cgroup/cpuset: v2 optimization Tejun Heo

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