Re: [PATCH 1/2] sched/uclamp: Add a new sysctl to control RT default boost value

From: Steven Rostedt <rostedt@goodmis.org>
To: Qais Yousef <qais.yousef@arm.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Patrick Bellasi <patrick.bellasi@matbug.net>,
	Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Jonathan Corbet <corbet@lwn.net>,
	Juri Lelli <juri.lelli@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
	Luis Chamberlain <mcgrof@kernel.org>,
	Kees Cook <keescook@chromium.org>,
	Iurii Zaikin <yzaikin@google.com>,
	Quentin Perret <qperret@google.com>,
	Valentin Schneider <valentin.schneider@arm.com>,
	Pavan Kondeti <pkondeti@codeaurora.org>,
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 1/2] sched/uclamp: Add a new sysctl to control RT default boost value
Date: Mon, 20 Apr 2020 20:52:10 -0400	[thread overview]
Message-ID: <20200420205210.7217651c@oasis.local.home> (raw)
In-Reply-To: <20200420151941.47ualxul5seqwdgh@e107158-lin.cambridge.arm.com>

On Mon, 20 Apr 2020 16:19:42 +0100
Qais Yousef <qais.yousef@arm.com> wrote:

> > root@h960:~# find / -name "*util_clamp*"
> > /proc/sys/kernel/sched_rt_default_util_clamp_min
> > /proc/sys/kernel/sched_util_clamp_max
> > /proc/sys/kernel/sched_util_clamp_min
> > 
> > IMHO, keeping the common 'sched_util_clamp_' would be helpful here, e.g.
> > 
> > /proc/sys/kernel/sched_util_clamp_rt_default_min  
> 
> All RT related knobs are prefixed with 'sched_rt'. I kept the 'util_clamp_min'
> coherent with the current sysctl (sched_util_clamp_min). Quentin suggested
> adding 'default' to be more obvious, so I ended up with
> 
> 	'sched_rt' + '_default' + '_util_clamp_min'.
> 
> I think this is the logical and most consistent form. Given that Patrick seems
> to be okay with the 'default' now, does this look good to you too?

There's only two files with "sched_rt" and they are tightly coupled
(they define how much an RT task may use the CPU).

My question is, is this "sched_rt_default_util_clamp_min" related in
any way to those other two files that start with "sched_rt", or is it
more related to the files that start with "sched_util_clamp"?

If the latter, then I would suggest using
"sched_util_clamp_min_rt_default", as it looks to be more related to
the "sched_util_clamp_min" than to anything else.

-- Steve