Re: [RFC PATCH v5 18/29] sched/core: Cgroup v2 support

[luca abeni]

Hi Peter,

On Tue, 5 May 2026 16:59:22 +0200
Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:

> On Thu, Apr 30, 2026 at 11:38:22PM +0200, Yuri Andriaccio wrote:
> > From: luca abeni <luca.abeni@xxxxxxxxxxxxxxx>
> > 
> > Make rt_runtime_us and rt_period_us virtual files accessible also
> > to the cgroup v2 controller, effectively enabling the
> > RT_GROUP_SCHED mechanism to cgroups v2.  
> 
> Can we have a blub about why only strict periodic servers; eg. why no
> sporadic? and such...

Maybe I am misunderstanding your question, anyway: the file is called
"rt_runtime_us", but the scheduling algorithm used to schedule the
cgroup is SCHED_DEADLINE.
So, we do not use a strictly periodic server, but a CBS, that can also
support sporadic / non-periodic activations.


			Luca

> 
> > Signed-off-by: luca abeni <luca.abeni@xxxxxxxxxxxxxxx>
> > Signed-off-by: Yuri Andriaccio <yurand2000@xxxxxxxxx>
> > ---
> >  kernel/sched/core.c | 12 ++++++++++++
> >  1 file changed, 12 insertions(+)
> > 
> > diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> > index 0c7032d254ba..3ffe3ac5071d 100644
> > --- a/kernel/sched/core.c
> > +++ b/kernel/sched/core.c
> > @@ -10245,6 +10245,18 @@ static struct cftype cpu_files[] = {
> >  		.write = cpu_uclamp_max_write,
> >  	},
> >  #endif /* CONFIG_UCLAMP_TASK_GROUP */
> > +#ifdef CONFIG_RT_GROUP_SCHED
> > +	{
> > +		.name = "rt_runtime_us",
> > +		.read_s64 = cpu_rt_runtime_read,
> > +		.write_s64 = cpu_rt_runtime_write,
> > +	},
> > +	{
> > +		.name = "rt_period_us",
> > +		.read_u64 = cpu_rt_period_read_uint,
> > +		.write_u64 = cpu_rt_period_write_uint,
> > +	},
> > +#endif /* CONFIG_RT_GROUP_SCHED */
> >  	{ }	/* terminate */
> >  };
> >  
> > -- 
> > 2.53.0
> >