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author | 2022-07-04 11:16:01 +0100 | |
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committer | 2022-07-04 16:23:16 +0100 | |
commit | bfcc4397435dc0407099b9a805391abc05c2313b (patch) | |
tree | 0ec3b4355558ce3bfb77ef0bb988077ca39a27c1 /drivers/base | |
parent | arch_topology: Don't set cluster identifier as physical package identifier (diff) | |
download | linux-bfcc4397435dc0407099b9a805391abc05c2313b.tar.gz linux-bfcc4397435dc0407099b9a805391abc05c2313b.tar.bz2 linux-bfcc4397435dc0407099b9a805391abc05c2313b.zip |
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')
-rw-r--r-- | drivers/base/arch_topology.c | 8 |
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; } |