| Message ID | 20220627165047.336669-17-sudeep.holla@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arch_topology: Updates to add socket support and fix cluster ids | expand |
On Mon, 27 Jun 2022 at 18:51, Sudeep Holla <sudeep.holla@arm.com> wrote: > > From: Ionela Voinescu <ionela.voinescu@arm.com> > > Currently the cluster identifier is not set on DT based platforms. > The reset or default value is -1 for all the CPUs. Once we assign the > cluster identifier values correctly, the cluster_sibling mask will be > populated and returned by cpu_clustergroup_mask() to contribute in the > creation of the CLS scheduling domain level, if SCHED_CLUSTER is > enabled. > > To avoid topologies that will result in questionable or incorrect > scheduling domains, impose restrictions regarding the span of clusters, > as presented to scheduling domains building code: cluster_sibling should > not span more or the same CPUs as cpu_coregroup_mask(). > > This is needed in order to obtain a strict separation between the MC and > CLS levels, and maintain the same domains for existing platforms in > the presence of CONFIG_SCHED_CLUSTER, where the new cluster information > is redundant and irrelevant for the scheduler. > > While previously the scheduling domain builder code would have removed MC > as redundant and kept CLS if SCHED_CLUSTER was enabled and the > cpu_coregroup_mask() and cpu_clustergroup_mask() spanned the same CPUs, > now CLS will be removed and MC kept. > > Link: https://lore.kernel.org/r/20220621192034.3332546-18-sudeep.holla@arm.com > Cc: Darren Hart <darren@os.amperecomputing.com> > Tested-by: Ionela Voinescu <ionela.voinescu@arm.com> > Signed-off-by: Ionela Voinescu <ionela.voinescu@arm.com> > Signed-off-by: Sudeep Holla <sudeep.holla@arm.com> > --- > drivers/base/arch_topology.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c > index 46fa1b70b02b..277b65cf3306 100644 > --- a/drivers/base/arch_topology.c > +++ b/drivers/base/arch_topology.c > @@ -686,6 +686,14 @@ const struct cpumask *cpu_coregroup_mask(int cpu) > > const struct cpumask *cpu_clustergroup_mask(int cpu) > { > + /* > + * Forbid cpu_clustergroup_mask() to span more or the same CPUs as > + * cpu_coregroup_mask(). > + */ > + if (cpumask_subset(cpu_coregroup_mask(cpu), > + &cpu_topology[cpu].cluster_sibling)) > + return get_cpu_mask(cpu); AFAICT, this will change the Altra scheduling topology which will now have a MC level instead of the CLS but it's probably not a problem as the flags are the same for now Acked-by: Vincent Guittot <vincent.guittot@linaro.org> > + > return &cpu_topology[cpu].cluster_sibling; > } > > -- > 2.36.1 >
diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c index 46fa1b70b02b..277b65cf3306 100644 --- a/drivers/base/arch_topology.c +++ b/drivers/base/arch_topology.c @@ -686,6 +686,14 @@ const struct cpumask *cpu_coregroup_mask(int cpu) const struct cpumask *cpu_clustergroup_mask(int cpu) { + /* + * Forbid cpu_clustergroup_mask() to span more or the same CPUs as + * cpu_coregroup_mask(). + */ + if (cpumask_subset(cpu_coregroup_mask(cpu), + &cpu_topology[cpu].cluster_sibling)) + return get_cpu_mask(cpu); + return &cpu_topology[cpu].cluster_sibling; }