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From: CGEL <cgel.zte@gmail.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: yzaikin@google.com, liu.hailong6@zte.com.cn, mingo@redhat.com,
	juri.lelli@redhat.com, vincent.guittot@linaro.org,
	dietmar.eggemann@arm.com, rostedt@goodmis.org,
	bsegall@google.com, mgorman@suse.de, bristot@redhat.com,
	mcgrof@kernel.org, keescook@chromium.org, pjt@google.com,
	yang.yang29@zte.com.cn, joshdon@google.com,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	Zeal Robot <zealci@zte.com.cm>
Subject: Re: [PATCH] sched: Add a new version sysctl to control child runs first
Date: Mon, 13 Sep 2021 11:37:31 +0000	[thread overview]
Message-ID: <613f37fc.1c69fb81.9092.a4f5@mx.google.com> (raw)
In-Reply-To: <YT8IQioxUARMus9w@hirez.programming.kicks-ass.net>

On Mon, Sep 13, 2021 at 10:13:54AM +0200, Peter Zijlstra wrote:
> On Sun, Sep 12, 2021 at 04:12:23AM +0000, cgel.zte@gmail.com wrote:
> > From: Yang Yang <yang.yang29@zte.com.cn>
> > 
> > The old version sysctl has some problems. First, it allows set value
> > bigger than 1, which is unnecessary. Second, it didn't follow the
> > rule of capabilities. Thirdly, it didn't use static key. This new
> > version fixes all the problems.
> 
> Does any of that actually matter?

For the first problem, I think the reason why sysctl_schedstats() only
accepts 0 or 1, is suitbale for sysctl_child_runs_first(). Since
task_fork_fair() only need sysctl_sched_child_runs_first to be
zero or non-zero.

For the second problem, I remember there is a rule: try to
administration system through capilities but not depends on
root identity. Just like sysctl_schedstats() or other
sysctl_xx().

For the thirdly problem, sysctl_child_runs_first maynot changes
often, but may accessed often, like static_key delayacct_key
controlled by sysctl_delayacct().

Thanks!

  reply	other threads:[~2021-09-13 11:37 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-12  4:12 [PATCH] sched: Add a new version sysctl to control child runs first cgel.zte
2021-09-13  8:13 ` Peter Zijlstra
2021-09-13 11:37   ` CGEL [this message]
2021-09-13 13:42     ` Peter Zijlstra
2021-09-14  4:05       ` CGEL
     [not found]       ` <20210914040524.GA141438@cgel.zte@gmail.com>
2021-10-07  3:26         ` CGEL

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