linux-kernel - Re: [PATCH 2/2] cgroup, docs: Document interaction of RT processes with cpu controller

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Message-ID: <2vvwedzioiopvjhah4jxlc6a5gq4uayyj2s5gtjs455yojkhnn@rkxanxmh3hmu>
Date: Mon, 10 Mar 2025 18:14:30 +0100
From: Michal Koutný <mkoutny@...e.com>
To: "Shashank.Mahadasyam@...y.com" <Shashank.Mahadasyam@...y.com>
Cc: Tejun Heo <tj@...nel.org>, Johannes Weiner <hannes@...xchg.org>, 
	Jonathan Corbet <corbet@....net>, Waiman Long <longman@...hat.com>, 
	"cgroups@...r.kernel.org" <cgroups@...r.kernel.org>, "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>, 
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "Shinya.Takumi@...y.com" <Shinya.Takumi@...y.com>
Subject: Re: [PATCH 2/2] cgroup, docs: Document interaction of RT processes
 with cpu controller

On Thu, Mar 06, 2025 at 11:02:22AM +0000, "Shashank.Mahadasyam@...y.com" <Shashank.Mahadasyam@...y.com> wrote:
> Do you think it should be rephrased to make it clearer?

Aha, I understand now why it confused you (with the paragraph about
realtime tasks right above interface files).

I'd consider such a minimal correction:

--- a/Documentation/admin-guide/cgroup-v2.rst
+++ b/Documentation/admin-guide/cgroup-v2.rst
@@ -1076,7 +1076,7 @@ cpufreq governor about the minimum desired frequency which should always be
 provided by a CPU, as well as the maximum desired frequency, which should not
 be exceeded by a CPU.

-WARNING: cgroup2 doesn't yet support control of realtime processes. For
+WARNING: cgroup2 doesn't yet support (bandwidth) control of realtime processes. For
 a kernel built with the CONFIG_RT_GROUP_SCHED option enabled for group
 scheduling of realtime processes, the cpu controller can only be enabled
 when all RT processes are in the root cgroup.  This limitation does


Of course wordier rewrite is possible but I find the text as you
originally proposed unclear due to several uses of "only" that imply
restrictions that aren't in place in reality.

Thanks,
Michal

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