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

From: Dietmar Eggemann
Date: Tue Apr 21 2020 - 07:16:21 EST


On 21/04/2020 02:52, Steven Rostedt wrote:
> On Mon, 20 Apr 2020 16:19:42 +0100
> Qais Yousef <qais.yousef@xxxxxxx> 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.

For me it's the latter.