Hi Srikar, On Tue, Jul 14, 2020 at 10:06:18AM +0530, Srikar Dronamraju wrote: > Current code assumes that cpumask of cpus sharing a l2-cache mask will > always be a superset of cpu_sibling_mask. > > Lets stop that assumption. > > Cc: linuxppc-dev <linuxppc-dev@lists.ozlabs.org> > Cc: Michael Ellerman <micha...@au1.ibm.com> > Cc: Nick Piggin <npig...@au1.ibm.com> > Cc: Oliver OHalloran <olive...@au1.ibm.com> > Cc: Nathan Lynch <nath...@linux.ibm.com> > Cc: Michael Neuling <mi...@linux.ibm.com> > Cc: Anton Blanchard <an...@au1.ibm.com> > Cc: Gautham R Shenoy <e...@linux.vnet.ibm.com> > Cc: Vaidyanathan Srinivasan <sva...@linux.ibm.com> > Signed-off-by: Srikar Dronamraju <sri...@linux.vnet.ibm.com> > --- > arch/powerpc/kernel/smp.c | 28 +++++++++++++++------------- > 1 file changed, 15 insertions(+), 13 deletions(-) > > diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c > index 7d430fc536cc..875f57e41355 100644 > --- a/arch/powerpc/kernel/smp.c > +++ b/arch/powerpc/kernel/smp.c > @@ -1198,6 +1198,7 @@ static bool update_mask_by_l2(int cpu, struct cpumask > *(*mask_fn)(int)) > struct device_node *l2_cache, *np; > int i; > > + cpumask_set_cpu(cpu, mask_fn(cpu));
It would be good to comment why do we need to do set the CPU in the l2-mask if we don't have a l2cache domain. > l2_cache = cpu_to_l2cache(cpu); > if (!l2_cache) > return false; > @@ -1284,29 +1285,30 @@ static void add_cpu_to_masks(int cpu) > * add it to it's own thread sibling mask. > */ > cpumask_set_cpu(cpu, cpu_sibling_mask(cpu)); > + cpumask_set_cpu(cpu, cpu_core_mask(cpu)); > > for (i = first_thread; i < first_thread + threads_per_core; i++) > if (cpu_online(i)) > set_cpus_related(i, cpu, cpu_sibling_mask); > > add_cpu_to_smallcore_masks(cpu); > - /* > - * Copy the thread sibling mask into the cache sibling mask > - * and mark any CPUs that share an L2 with this CPU. > - */ > - for_each_cpu(i, cpu_sibling_mask(cpu)) > - set_cpus_related(cpu, i, cpu_l2_cache_mask); > update_mask_by_l2(cpu, cpu_l2_cache_mask); > > - /* > - * Copy the cache sibling mask into core sibling mask and mark > - * any CPUs on the same chip as this CPU. > - */ > - for_each_cpu(i, cpu_l2_cache_mask(cpu)) > - set_cpus_related(cpu, i, cpu_core_mask); > + if (pkg_id == -1) { > + struct cpumask *(*mask)(int) = cpu_sibling_mask; > + > + /* > + * Copy the sibling mask into core sibling mask and > + * mark any CPUs on the same chip as this CPU. > + */ > + if (shared_caches) > + mask = cpu_l2_cache_mask; > + Now that we decoupling the containment relationship between sibling_mask and l2-cache mask, should we set all the CPUs that are both in cpu_sibling_mask(cpu) as well as cpu_l2_mask(cpu) in cpu_core_mask ? > + for_each_cpu(i, mask(cpu)) > + set_cpus_related(cpu, i, cpu_core_mask); > > - if (pkg_id == -1) > return; > + } > > for_each_cpu(i, cpu_online_mask) > if (get_physical_package_id(i) == pkg_id) > -- > 2.17.1 > -- Thanks and Regards gautham.