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    SubjectRe: [PATCH v3 10/16] arch_topology: Set thread sibling cpumask only within the cluster
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    On 5/25/22 4:14 PM, Sudeep Holla wrote:
    > Currently the cluster identifier is not set on the DT based platforms.
    > The reset or default value is -1 for all the CPUs. Once we assign the
    > cluster identifier values correctly that imay result in getting the thread
    > siblings wrongs as the core identifiers can be same for 2 different CPUs
    > belonging to 2 different cluster.
    >
    > So, in order to get the thread sibling cpumasks correct, we need to
    > update them only if the cores they belong are in the same cluster within
    > the socket. Let us skip updation of the thread sibling cpumaks if the
    > cluster identifier doesn't match.
    >
    > This change won't affect even if the cluster identifiers are not set
    > currently but will avoid any breakage once we set the same correctly.
    >
    > Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
    > ---
    > drivers/base/arch_topology.c | 12 +++++++-----
    > 1 file changed, 7 insertions(+), 5 deletions(-)
    >

    Reviewed-by: Gavin Shan <gshan@redhat.com>
    Tested-by: Gavin Shan <gshan@redhat.com>

    > diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
    > index 76c702c217c5..59dc2c80c439 100644
    > --- a/drivers/base/arch_topology.c
    > +++ b/drivers/base/arch_topology.c
    > @@ -703,15 +703,17 @@ void update_siblings_masks(unsigned int cpuid)
    > if (cpuid_topo->package_id != cpu_topo->package_id)
    > continue;
    >
    > - if (cpuid_topo->cluster_id == cpu_topo->cluster_id &&
    > - cpuid_topo->cluster_id != -1) {
    > + cpumask_set_cpu(cpuid, &cpu_topo->core_sibling);
    > + cpumask_set_cpu(cpu, &cpuid_topo->core_sibling);
    > +
    > + if (cpuid_topo->cluster_id != cpu_topo->cluster_id)
    > + continue;
    > +
    > + if (cpuid_topo->cluster_id != -1) {
    > cpumask_set_cpu(cpu, &cpuid_topo->cluster_sibling);
    > cpumask_set_cpu(cpuid, &cpu_topo->cluster_sibling);
    > }
    >
    > - cpumask_set_cpu(cpuid, &cpu_topo->core_sibling);
    > - cpumask_set_cpu(cpu, &cpuid_topo->core_sibling);
    > -
    > if (cpuid_topo->core_id != cpu_topo->core_id)
    > continue;
    >
    >

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