linux-kernel - Re: [PATCH v2 2/5] sched/numa: Replace runnable_load_avg by load

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Date:   Tue, 18 Feb 2020 15:17:08 +0100
From:   Vincent Guittot <vincent.guittot@...aro.org>
To:     Mel Gorman <mgorman@...e.de>
Cc:     Dietmar Eggemann <dietmar.eggemann@....com>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ben Segall <bsegall@...gle.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Phil Auld <pauld@...hat.com>, Parth Shah <parth@...ux.ibm.com>,
        Valentin Schneider <valentin.schneider@....com>,
        Hillf Danton <hdanton@...a.com>
Subject: Re: [PATCH v2 2/5] sched/numa: Replace runnable_load_avg by load_avg

On Tue, 18 Feb 2020 at 14:51, Mel Gorman <mgorman@...e.de> wrote:
>
> On Tue, Feb 18, 2020 at 01:37:45PM +0100, Dietmar Eggemann wrote:
> > On 14/02/2020 16:27, Vincent Guittot wrote:
> >
> > [...]
> >
> > >     /*
> > >      * The load is corrected for the CPU capacity available on each node.
> > >      *
> > > @@ -1788,10 +1831,10 @@ static int task_numa_migrate(struct task_struct *p)
> > >     dist = env.dist = node_distance(env.src_nid, env.dst_nid);
> > >     taskweight = task_weight(p, env.src_nid, dist);
> > >     groupweight = group_weight(p, env.src_nid, dist);
> > > -   update_numa_stats(&env.src_stats, env.src_nid);
> > > +   update_numa_stats(&env, &env.src_stats, env.src_nid);
> >
> > This looks strange. Can you do:
> >
> > -static void update_numa_stats(struct task_numa_env *env,
> > +static void update_numa_stats(unsigned int imbalance_pct,
> >                               struct numa_stats *ns, int nid)
> >
> > -    update_numa_stats(&env, &env.src_stats, env.src_nid);
> > +    update_numa_stats(env.imbalance_pct, &env.src_stats, env.src_nid);
> >
>
> You'd also have to pass in env->p and while it could be done, I do not
> think its worthwhile.

I agree

>
> > [...]
> >
> > > +static unsigned long cpu_runnable_load(struct rq *rq)
> > > +{
> > > +   return cfs_rq_runnable_load_avg(&rq->cfs);
> > > +}
> > > +
> >
> > Why not remove cpu_runnable_load() in this patch rather moving it?
> >
> > kernel/sched/fair.c:5492:22: warning: ???cpu_runnable_load??? defined but
> > not used [-Wunused-function]
> >  static unsigned long cpu_runnable_load(struct rq *rq)
> >
>
> I took the liberty of addressing that when I picked up Vincent's patches
> for "Reconcile NUMA balancing decisions with the load balancer v3" to fix
> a build warning. I did not highlight it when I posted because it was such
> a trivial change.

yes I have noticed that.
Thanks

>
> --
> Mel Gorman
> SUSE Labs