linux-kernel - Re: [PATCH 2/2] cgroup, docs: Document interaction of RT processes with cpu controller

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Message-ID:
 <OSZPR01MB6711219F264C5EAC2CE1512A93CA2@OSZPR01MB6711.jpnprd01.prod.outlook.com>
Date: Thu, 6 Mar 2025 10:23:03 +0000
From: "Shashank.Mahadasyam@...y.com" <Shashank.Mahadasyam@...y.com>
To: Waiman Long <llong@...hat.com>
CC: "cgroups@...r.kernel.org" <cgroups@...r.kernel.org>,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Shinya.Takumi@...y.com" <Shinya.Takumi@...y.com>,
        Tejun Heo <tj@...nel.org>, Johannes Weiner <hannes@...xchg.org>,
        Jonathan Corbet <corbet@....net>,
        Michal Koutný <mkoutny@...e.com>,
        "Shashank.Mahadasyam@...y.com" <Shashank.Mahadasyam@...y.com>
Subject: Re: [PATCH 2/2] cgroup, docs: Document interaction of RT processes
 with cpu controller

Hi Longman,

> > From: Shashank Balaji <shashank.mahadasyam@...y.com>
> >
> > If the cpu controller is enabled in a CONFIG_RT_GROUP_SCHED
> > disabled setting, cpu.stat and cpu.pressure account for realtime
> > processes, and cpu.uclamp.{min, max} affect realtime processes as well.
> > None of the other interface files are affected by or affect realtime
> > processes.
> >
> > Signed-off-by: Shashank Balaji <shashank.mahadasyam@...y.com>
> > ---
> >   Documentation/admin-guide/cgroup-v2.rst | 18 +++++++++++++-----
> >   1 file changed, 13 insertions(+), 5 deletions(-)
> >
> > diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
> > index f293a13b42ed69e7c6bf5e974cb86e228411af4e..2c267f42e5fef9c4e2c3530ce73330d680b9b2dc 100644
> > --- a/Documentation/admin-guide/cgroup-v2.rst
> > +++ b/Documentation/admin-guide/cgroup-v2.rst
> > @@ -1095,7 +1095,9 @@ realtime processes irrespective of CONFIG_RT_GROUP_SCHED.
> >   CPU Interface Files
> >   ~~~~~~~~~~~~~~~~~~~
> >   
> > -All time durations are in microseconds.
> > +All time durations are in microseconds. Only cpu.stat and cpu.pressure account
> > +for realtime processes, and only cpu.uclamp.min and cpu.uclamp.max
> > +affect realtime processes.
> >   
> >     cpu.stat
> >   	A read-only flat-keyed file.
> > @@ -1115,6 +1117,9 @@ All time durations are in microseconds.
> >   	- nr_bursts
> >   	- burst_usec
> >   
> > +    The runtime of realtime processes is accounted for only by the usage_usec,
> > +	user_usec, and system_usec fields.
> > +
> 
> Alignment problem!
> 
> Anyway, I am not familiar enough with these cpu control files to give a 
> review yet.
> 
> Cheers,
> Longman

My bad, I'll fix the alignment.

Thanks,
Shashank