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From: Ingo Molnar <mingo@kernel.org>
To: Cyril Hrubis <chrubis@suse.cz>
Cc: Juri Lelli <juri.lelli@redhat.com>,
	Valentin Schneider <vschneid@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Peter Zijlstra <peterz@infradead.org>,
	linux-kernel@vger.kernel.org,
	Steven Rostedt <rostedt@goodmis.org>,
	Ben Segall <bsegall@google.com>, Ingo Molnar <mingo@redhat.com>,
	Mel Gorman <mgorman@suse.de>,
	Daniel Bristot de Oliveira <bristot@redhat.com>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	ltp@lists.linux.it
Subject: Re: [LTP] [PATCH] sched/rt: Disallow writing invalid values to sched_rt_period_us
Date: Fri, 22 Sep 2023 11:46:17 +0200	[thread overview]
Message-ID: <ZQ1iabFEs93OZMSE@gmail.com> (raw)
In-Reply-To: <ZPIqsmTbJh7z-LcO@yuki>


* Cyril Hrubis <chrubis@suse.cz> wrote:

> Hi!
> > Documentation/scheduller/sched-rt-group.rst [1] specifies this as values from -1 to
> > (INT_MAX - 1), I guess due int range. Looking into proc_dointvec_minmax() [2]
> > even INT_MAX would pass the check. I suppose we can do nothing about that,
> > because there is no value in sysctl_vals[] which would represent INT_MAX - 1.
> > 
> > And you specify in LTP test range: from -1 to INT_MAX.
> > 
> > But even much shorter value than INT_MAX fails:
> > 
> > $ echo 1234567 > /proc/sys/kernel/sched_rt_runtime_us
> > sh: echo: write error: Invalid argument
> 
> That is because runtime_us must be < period_us by definition, since
> runtime_us defines how much time is allocated from the period_us. I
> guess that this is not described good enough in the kernel docs.

Mind adding a second patch to your series, clarifying 
Documentation/scheduler/sched-rt-group.rst?

Thanks,

	Ingo

-- 
Mailing list info: https://lists.linux.it/listinfo/ltp

  parent reply	other threads:[~2023-09-22  9:46 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-01 15:43 [LTP] [PATCH] sched/rt: Disallow writing invalid values to sched_rt_period_us Cyril Hrubis
2023-09-01 17:45 ` Petr Vorel
2023-09-01 18:17   ` Cyril Hrubis
2023-09-02 20:22     ` Petr Vorel
2023-09-22  9:46     ` Ingo Molnar [this message]
2023-09-22 11:43       ` Cyril Hrubis

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