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authorIonela Voinescu <ionela.voinescu@arm.com>2022-07-04 13:16:01 +0300
committerSudeep Holla <sudeep.holla@arm.com>2022-07-04 18:23:16 +0300
commitbfcc4397435dc0407099b9a805391abc05c2313b (patch)
tree0ec3b4355558ce3bfb77ef0bb988077ca39a27c1 /drivers/base/arch_topology.c
parent26a2b73a7b15a51ec1409648c9b43882f66fbacf (diff)
downloadlinux-bfcc4397435dc0407099b9a805391abc05c2313b.tar.xz
arch_topology: Limit span of cpu_clustergroup_mask()
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/20220704101605.1318280-18-sudeep.holla@arm.com Cc: Darren Hart <darren@os.amperecomputing.com> Tested-by: Conor Dooley <conor.dooley@microchip.com> Acked-by: Vincent Guittot <vincent.guittot@linaro.org> Signed-off-by: Ionela Voinescu <ionela.voinescu@arm.com> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Diffstat (limited to 'drivers/base/arch_topology.c')
-rw-r--r--drivers/base/arch_topology.c8
1 files changed, 8 insertions, 0 deletions
diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
index e384afb6cac7..591c1f8e15e2 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;
}