linux-kernel - Re: [PATCH v2 09/10] Powerpc/smp: Create coregroup domain

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Message-ID: <20200722072943.GD9290@linux.vnet.ibm.com>
Date:   Wed, 22 Jul 2020 12:59:43 +0530
From:   Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
To:     Gautham R Shenoy <ego@...ux.vnet.ibm.com>
Cc:     Michael Ellerman <michaele@....ibm.com>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Valentin Schneider <valentin.schneider@....com>,
        Nick Piggin <npiggin@....ibm.com>,
        Oliver OHalloran <oliveroh@....ibm.com>,
        Nathan Lynch <nathanl@...ux.ibm.com>,
        Michael Neuling <mikey@...ux.ibm.com>,
        Anton Blanchard <anton@....ibm.com>,
        Vaidyanathan Srinivasan <svaidy@...ux.ibm.com>,
        Jordan Niethe <jniethe5@...il.com>
Subject: Re: [PATCH v2 09/10] Powerpc/smp: Create coregroup domain

> > @@ -1386,6 +1421,9 @@ int setup_profiling_timer(unsigned int multiplier)
> > 
> >  static void fixup_topology(void)
> >  {
> > +	if (!has_coregroup_support())
> > +		powerpc_topology[mc_idx].mask = cpu_bigcore_mask;
> > +
> 
> Shouldn't we move this condition after doing the fixup for shared
> caches ? Because if we have shared_caches, but not core_group, then we
> want the coregroup domain to degenerate correctly.
> 

Currently we aren't consolidating, and hence the order doesn't matter for
degeneration. However even if in future, if we want to consolidate the
domains before calling set_sched_topology(), this order would be ideal.

> 
> >  	if (shared_caches) {
> >  		pr_info("Using shared cache scheduler topology\n");
> >  		powerpc_topology[bigcore_idx].mask = shared_cache_mask;
> 

-- 
Thanks and Regards
Srikar Dronamraju