2022-06-21 19:23:44

by Sudeep Holla

Subject: [PATCH v4 12/20] arch_topology: Set thread sibling cpumask only within the cluster

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.

Reviewed-by: Gavin Shan <[email protected]>
Tested-by: Gavin Shan <[email protected]>
Signed-off-by: Sudeep Holla <[email protected]>
---
drivers/base/arch_topology.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
index b63cc52e12ce..7a5ff1ea5f00 100644
--- a/drivers/base/arch_topology.c
+++ b/drivers/base/arch_topology.c
@@ -708,15 +708,17 @@ 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;

--
2.36.1

2022-06-27 13:47:42

by Ionela Voinescu

Subject: Re: [PATCH v4 12/20] arch_topology: Set thread sibling cpumask only within the cluster

On Tuesday 21 Jun 2022 at 20:20:26 (+0100), 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
^^^^
Nit: may
> siblings wrongs as the core identifiers can be same for 2 different CPUs
Nit: ^^^^^^
wrong


Thanks,
Ionela.

> 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.
>
> Reviewed-by: Gavin Shan <[email protected]>
> Tested-by: Gavin Shan <[email protected]>
> Signed-off-by: Sudeep Holla <[email protected]>
> ---
> drivers/base/arch_topology.c | 12 +++++++-----
> 1 file changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
> index b63cc52e12ce..7a5ff1ea5f00 100644
> --- a/drivers/base/arch_topology.c
> +++ b/drivers/base/arch_topology.c
> @@ -708,15 +708,17 @@ 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;
>
> --
> 2.36.1
>