From: Cyril Hrubis <chrubis@suse.cz>
To: Petr Vorel <pvorel@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, 1 Sep 2023 20:17:22 +0200 [thread overview]
Message-ID: <ZPIqsmTbJh7z-LcO@yuki> (raw)
In-Reply-To: <20230901174529.GB364687@pevik>
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.
--
Cyril Hrubis
chrubis@suse.cz
--
Mailing list info: https://lists.linux.it/listinfo/ltp
next prev parent reply other threads:[~2023-09-01 18:17 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 [this message]
2023-09-02 20:22 ` Petr Vorel
2023-09-22 9:46 ` Ingo Molnar
2023-09-22 11:43 ` Cyril Hrubis
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