linux-kernel - Re: [Patch v3 2/6] sched/topology: Record number of cores in sched group

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Date:   Tue, 11 Jul 2023 13:31:58 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Tim Chen <tim.c.chen@...ux.intel.com>
Cc:     Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Ricardo Neri <ricardo.neri@...el.com>,
        "Ravi V . Shankar" <ravi.v.shankar@...el.com>,
        Ben Segall <bsegall@...gle.com>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Len Brown <len.brown@...el.com>, Mel Gorman <mgorman@...e.de>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Valentin Schneider <vschneid@...hat.com>,
        Ionela Voinescu <ionela.voinescu@....com>, x86@...nel.org,
        linux-kernel@...r.kernel.org,
        Shrikanth Hegde <sshegde@...ux.vnet.ibm.com>,
        Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
        naveen.n.rao@...ux.vnet.ibm.com,
        Yicong Yang <yangyicong@...ilicon.com>,
        Barry Song <v-songbaohua@...o.com>,
        Chen Yu <yu.c.chen@...el.com>, Hillf Danton <hdanton@...a.com>
Subject: Re: [Patch v3 2/6] sched/topology: Record number of cores in sched
 group

On Mon, Jul 10, 2023 at 03:40:34PM -0700, Tim Chen wrote:
> On Fri, 2023-07-07 at 15:57 -0700, Tim Chen wrote:
> > From: Tim C Chen <tim.c.chen@...ux.intel.com>
> > 
> > When balancing sibling domains that have different number of cores,
> > tasks in respective sibling domain should be proportional to the number
> > of cores in each domain. In preparation of implementing such a policy,
> > record the number of tasks in a scheduling group.
> 
> Caught a typo.  Should be "the number of cores" instead of
> "the number of tasks" in a scheduling group.
> 
> Peter, should I send you another patch with the corrected commit log?

I'll fix it up, already had to fix the patch because due to robot
finding a compile fail for SCHED_SMT=n builds.



> > @@ -1275,14 +1275,22 @@ build_sched_groups(struct sched_domain *sd, int cpu)
> >  static void init_sched_groups_capacity(int cpu, struct sched_domain *sd)
> >  {
> >  	struct sched_group *sg = sd->groups;
> > +	struct cpumask *mask = sched_domains_tmpmask2;
> >  
> >  	WARN_ON(!sg);
> >  
> >  	do {
> > -		int cpu, max_cpu = -1;
> > +		int cpu, cores = 0, max_cpu = -1;
> >  
> >  		sg->group_weight = cpumask_weight(sched_group_span(sg));
> >  
> > +		cpumask_copy(mask, sched_group_span(sg));
> > +		for_each_cpu(cpu, mask) {
> > +			cores++;
#ifdef CONFIG_SCHED_SMT
> > +			cpumask_andnot(mask, mask, cpu_smt_mask(cpu));
#else
			__cpumask_clear_cpu(cpu, mask);
#endif

or something along them lines -- should be in queue.git/sched/core
already.

> > +		}
> > +		sg->cores = cores;
> > +
> >  		if (!(sd->flags & SD_ASYM_PACKING))
> >  			goto next;
> >  
>