Hi Jeremy,

On 2017/9/19 2:54, Jeremy Linton wrote:

Hi,


On 09/17/2017 08:50 PM, Xiongfeng Wang wrote:

quoted

Hi Jeremy,

On 2017/9/15 2:49, Jeremy Linton wrote:

quoted

Many modern machines have cluster on die (COD) non-uniformity
as well as the traditional multi-socket architectures. Reusing
the multi-socket or NUMA on die concepts for these (as arm64 does)
breaks down when presented with actual multi-socket/COD machines.
Similar, problems are also visible on some x86 machines so it
seems appropriate to start abstracting and making these topologies
visible.

To start, a topology_cod_id() macro is added which defaults to returning
the same information as topology_physical_package_id(). Moving forward
we can start to spit out the differences.

For arm64, an additional package_id is added to the cpu_topology array.
Initially this will be equal to the cluster_id as well.

Signed-off-by: Jeremy Linton <redacted>
---
  arch/arm64/include/asm/topology.h | 4 +++-
  arch/arm64/kernel/topology.c      | 8 ++++++--
  include/linux/topology.h          | 3 +++
  3 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/topology.h b/arch/arm64/include/asm/topology.h
index 8b57339823e9..bd7517960d39 100644
--- a/arch/arm64/include/asm/topology.h
+++ b/arch/arm64/include/asm/topology.h

@@ -7,13 +7,15 @@ struct cpu_topology {
      int thread_id;
      int core_id;
      int cluster_id;
+    int package_id;
      cpumask_t thread_sibling;
      cpumask_t core_sibling;
  };

'core_sibling' will be updated by 'update_siblings_masks()' to represent cores in a cluster;
Can we add a cpumask_t field to represent cores in a package? So that 'lstopo' can use this
cpumask_t to display the right information.

So, the change below modifies update_siblings_mask() to utilize the package_id. Per the ABI the ..cpuX/topology/physical_package_id is shared between the core_siblings/core_siblings_list. What physical_package_id means can vary per architecture, but the siblings list needs to be the cores with the same phyiscal_package (AFAIK, feel free to correct my understanding). That rule should be enforced by this patch set.

I suspect if your running these patches, and the lstopo output looks strange its because your on a machine where the thread_id has been assigned the cluster_id in the later patch set.

Sorry, I didn't notice your change in 'update_siblings_masks()' before, so 'core_sibling' are represent cores in a package now.
But we may need another cpumask_t field to represent cores in a cluster, so that the scheduler can use it to build a sched_domain
only with cores in one cluster.

quoted

Thanks,
Xiongfeng Wang

quoted

    extern struct cpu_topology cpu_topology[NR_CPUS];
  -#define topology_physical_package_id(cpu)    (cpu_topology[cpu].cluster_id)
+#define topology_physical_package_id(cpu)    (cpu_topology[cpu].package_id)
+#define topology_cod_id(cpu)        (cpu_topology[cpu].cluster_id)
  #define topology_core_id(cpu)        (cpu_topology[cpu].core_id)
  #define topology_core_cpumask(cpu)    (&cpu_topology[cpu].core_sibling)
  #define topology_sibling_cpumask(cpu)    (&cpu_topology[cpu].thread_sibling)

diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c
index 8d48b233e6ce..9147e5b6326d 100644
--- a/arch/arm64/kernel/topology.c
+++ b/arch/arm64/kernel/topology.c

@@ -67,6 +67,8 @@ static int __init parse_core(struct device_node *core, int cluster_id,
              leaf = false;
              cpu = get_cpu_for_node(t);
              if (cpu >= 0) {
+                /* maintain DT cluster == package behavior */
+                cpu_topology[cpu].package_id = cluster_id;
                  cpu_topology[cpu].cluster_id = cluster_id;
                  cpu_topology[cpu].core_id = core_id;
                  cpu_topology[cpu].thread_id = i;

@@ -88,7 +90,7 @@ static int __init parse_core(struct device_node *core, int cluster_id,
                     core);
              return -EINVAL;
          }
-
+        cpu_topology[cpu].package_id = cluster_id;
          cpu_topology[cpu].cluster_id = cluster_id;
          cpu_topology[cpu].core_id = core_id;
      } else if (leaf) {

@@ -228,7 +230,7 @@ static void update_siblings_masks(unsigned int cpuid)
      for_each_possible_cpu(cpu) {
          cpu_topo = &cpu_topology[cpu];
  -        if (cpuid_topo->cluster_id != cpu_topo->cluster_id)
+        if (cpuid_topo->package_id != cpu_topo->package_id)

(note here that core_siblings now reflect the package_id rather than the cluster_id. This only matters if cluster_id!=package_id).

quoted

quoted

              continue;
            cpumask_set_cpu(cpuid, &cpu_topo->core_sibling);

@@ -273,6 +275,7 @@ void store_cpu_topology(unsigned int cpuid)
                       MPIDR_AFFINITY_LEVEL(mpidr, 2) << 8 |
                       MPIDR_AFFINITY_LEVEL(mpidr, 3) << 16;
      }
+    cpuid_topo->package_id = cpuid_topo->cluster_id;
        pr_debug("CPU%u: cluster %d core %d thread %d mpidr %#016llx\n",
           cpuid, cpuid_topo->cluster_id, cpuid_topo->core_id,

@@ -292,6 +295,7 @@ static void __init reset_cpu_topology(void)
          cpu_topo->thread_id = -1;
          cpu_topo->core_id = 0;
          cpu_topo->cluster_id = -1;
+        cpu_topo->package_id = -1;
            cpumask_clear(&cpu_topo->core_sibling);
          cpumask_set_cpu(cpu, &cpu_topo->core_sibling);

diff --git a/include/linux/topology.h b/include/linux/topology.h
index cb0775e1ee4b..4660749a7303 100644
--- a/include/linux/topology.h
+++ b/include/linux/topology.h

@@ -184,6 +184,9 @@ static inline int cpu_to_mem(int cpu)
  #ifndef topology_physical_package_id
  #define topology_physical_package_id(cpu)    ((void)(cpu), -1)
  #endif
+#ifndef topology_cod_id                /* cluster on die */
+#define topology_cod_id(cpu)            topology_physical_package_id(cpu)
+#endif
  #ifndef topology_core_id
  #define topology_core_id(cpu)            ((void)(cpu), 0)
  #endif

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