linux-kernel - Re: [PATCH v2] sched/isolation: Prefer housekeeping cpu in local node

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Date:   Fri, 21 Jun 2019 15:21:54 +0800
From:   Wanpeng Li <kernellwp@...il.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>, Ingo Molnar <mingo@...hat.com>,
        Frederic Weisbecker <frederic@...nel.org>
Subject: Re: [PATCH v2] sched/isolation: Prefer housekeeping cpu in local node

On Fri, 21 Jun 2019 at 14:58, Peter Zijlstra <peterz@...radead.org> wrote:
>
> On Fri, Jun 21, 2019 at 09:35:11AM +0800, Wanpeng Li wrote:
> > From: Wanpeng Li <wanpengli@...cent.com>
> >
> > In real product setup, there will be houseeking cpus in each nodes, it
> > is prefer to do housekeeping from local node, fallback to global online
> > cpumask if failed to find houseeking cpu from local node.
> >
> > Cc: Ingo Molnar <mingo@...hat.com>
> > Cc: Peter Zijlstra <peterz@...radead.org>
> > Cc: Frederic Weisbecker <frederic@...nel.org>
> > Signed-off-by: Wanpeng Li <wanpengli@...cent.com>
>
> Looks good; did it actually work? :-)

Yeah, it works! :)

>
> > diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
> > index 63184cf..3d3fb04 100644
> > --- a/kernel/sched/topology.c
> > +++ b/kernel/sched/topology.c
> > @@ -1726,6 +1726,20 @@ void sched_domains_numa_masks_clear(unsigned int cpu)
> >
> >  #endif /* CONFIG_NUMA */
>
>
> Please double check this function; I wrote it in a hurry :-) Also maybe

So smart. :)

> add a wee comment on top like:
>
> /*
>  * sched_numa_file_closest() - given the NUMA topology, find the cpu
>  *                             closest to @cpu from @cpumask.
>  * cpumask: cpumask to find a cpu from
>  * cpu: cpu to be close to
>  *
>  * returns: cpu, or >= nr_cpu_ids when nothing found (or !NUMA).
>  */
>

Will do in v3.

Regards,
Wanpeng Li

> > +int sched_numa_find_closest(const struct cpumask *cpus, int cpu)
> > +{
> > +#ifdef CONFIG_NUMA
> > +     int i, j = cpu_to_node(cpu);
> > +
> > +     for (i = 0; i < sched_domains_numa_levels; i++) {
> > +             cpu = cpumask_any_and(cpus, sched_domains_numa_masks[i][j]);
> > +             if (cpu < nr_cpu_ids)
> > +                     return cpu;
> > +     }
> > +#endif
> > +     return nr_cpu_ids;
> > +}