Re: [RFC PATCH v1 1/2] sched: unified sched_powersavings sysfstunable

From: Vaidyanathan Srinivasan
Date: Fri Jan 27 2012 - 04:22:18 EST


* Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> [2012-01-25 16:10:13]:

> On Mon, 2012-01-16 at 21:52 +0530, Vaidyanathan Srinivasan wrote:
> > @@ -6150,10 +6150,8 @@ SD_INIT_FUNC(CPU)
> > SD_INIT_FUNC(ALLNODES)
> > SD_INIT_FUNC(NODE)
> > #endif
> > -#ifdef CONFIG_SCHED_SMT
> > +#ifdef CONFIG_SCHED_POWERSAVE
> > SD_INIT_FUNC(SIBLING)
> > -#endif
> > -#ifdef CONFIG_SCHED_MC
> > SD_INIT_FUNC(MC)
> > #endif
> > #ifdef CONFIG_SCHED_BOOK
> > @@ -6250,7 +6248,7 @@ static void claim_allocations(int cpu, struct sched_domain *sd)
> > *per_cpu_ptr(sdd->sgp, cpu) = NULL;
> > }
> >
> > -#ifdef CONFIG_SCHED_SMT
> > +#ifdef CONFIG_SCHED_POWERSAVE
> > static const struct cpumask *cpu_smt_mask(int cpu)
> > {
> > return topology_thread_cpumask(cpu);
> > @@ -6261,10 +6259,8 @@ static const struct cpumask *cpu_smt_mask(int cpu)
> > * Topology list, bottom-up.
> > */
> > static struct sched_domain_topology_level default_topology[] = {
> > -#ifdef CONFIG_SCHED_SMT
> > +#ifdef CONFIG_SCHED_POWERSAVE
> > { sd_init_SIBLING, cpu_smt_mask, },
> > -#endif
> > -#ifdef CONFIG_SCHED_MC
> > { sd_init_MC, cpu_coregroup_mask, },
> > #endif
> > #ifdef CONFIG_SCHED_BOOK
>
> I don't like this either, SCHED_{MC,SMT} here have nothing to do with
> powersavings, its topology support.

Yes, but we don't need these domains for any other purpose other than
powersave balance. The code overheads are not high, I will remove
the config option and check.

--Vaidy

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