[PATCH v5 09/10] powerpc/smp: Create coregroup domain

From: Srikar Dronamraju
Date: Mon Aug 10 2020 - 03:19:36 EST


Add percpu coregroup maps and masks to create coregroup domain.
If a coregroup doesn't exist, the coregroup domain will be degenerated
in favour of SMT/CACHE domain. Do note this patch is only creating stubs
for cpu_to_coregroup_id. The actual cpu_to_coregroup_id implementation
would be in a subsequent patch.

Cc: linuxppc-dev <linuxppc-dev@xxxxxxxxxxxxxxxx>
Cc: LKML <linux-kernel@xxxxxxxxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
Cc: Anton Blanchard <anton@xxxxxxxxxx>
Cc: Oliver O'Halloran <oohall@xxxxxxxxx>
Cc: Nathan Lynch <nathanl@xxxxxxxxxxxxx>
Cc: Michael Neuling <mikey@xxxxxxxxxxx>
Cc: Gautham R. Shenoy <ego@xxxxxxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Valentin Schneider <valentin.schneider@xxxxxxx>
Cc: Jordan Niethe <jniethe5@xxxxxxxxx>
Cc: Vaidyanathan Srinivasan <svaidy@xxxxxxxxxxxxx>
Reviewed-by: Gautham R. Shenoy <ego@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx>
---
Changelog v4 ->v5:
Updated commit msg to specify actual implementation of
cpu_to_coregroup_id is in a subsequent patch (Michael Ellerman)

Changelog v3 ->v4:
if coregroup_support doesn't exist, update MC mask to the next
smaller domain mask.

Changelog v2 -> v3:
Add optimization for mask updation under coregroup_support

Changelog v1 -> v2:
Moved coregroup topology fixup to fixup_topology (Gautham)

arch/powerpc/include/asm/topology.h | 10 ++++++
arch/powerpc/kernel/smp.c | 54 ++++++++++++++++++++++++++++-
arch/powerpc/mm/numa.c | 5 +++
3 files changed, 68 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/topology.h b/arch/powerpc/include/asm/topology.h
index f0b6300e7dd3..6609174918ab 100644
--- a/arch/powerpc/include/asm/topology.h
+++ b/arch/powerpc/include/asm/topology.h
@@ -88,12 +88,22 @@ static inline int cpu_distance(__be32 *cpu1_assoc, __be32 *cpu2_assoc)

#if defined(CONFIG_NUMA) && defined(CONFIG_PPC_SPLPAR)
extern int find_and_online_cpu_nid(int cpu);
+extern int cpu_to_coregroup_id(int cpu);
#else
static inline int find_and_online_cpu_nid(int cpu)
{
return 0;
}

+static inline int cpu_to_coregroup_id(int cpu)
+{
+#ifdef CONFIG_SMP
+ return cpu_to_core_id(cpu);
+#else
+ return 0;
+#endif
+}
+
#endif /* CONFIG_NUMA && CONFIG_PPC_SPLPAR */

#include <asm-generic/topology.h>
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 0536ac06876b..566e3accac3e 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -80,12 +80,22 @@ DEFINE_PER_CPU(cpumask_var_t, cpu_sibling_map);
DEFINE_PER_CPU(cpumask_var_t, cpu_smallcore_map);
DEFINE_PER_CPU(cpumask_var_t, cpu_l2_cache_map);
DEFINE_PER_CPU(cpumask_var_t, cpu_core_map);
+DEFINE_PER_CPU(cpumask_var_t, cpu_coregroup_map);

EXPORT_PER_CPU_SYMBOL(cpu_sibling_map);
EXPORT_PER_CPU_SYMBOL(cpu_l2_cache_map);
EXPORT_PER_CPU_SYMBOL(cpu_core_map);
EXPORT_SYMBOL_GPL(has_big_cores);

+enum {
+#ifdef CONFIG_SCHED_SMT
+ smt_idx,
+#endif
+ cache_idx,
+ mc_idx,
+ die_idx,
+};
+
#define MAX_THREAD_LIST_SIZE 8
#define THREAD_GROUP_SHARE_L1 1
struct thread_groups {
@@ -861,11 +871,27 @@ static const struct cpumask *smallcore_smt_mask(int cpu)
}
#endif

+static struct cpumask *cpu_coregroup_mask(int cpu)
+{
+ return per_cpu(cpu_coregroup_map, cpu);
+}
+
+static bool has_coregroup_support(void)
+{
+ return coregroup_enabled;
+}
+
+static const struct cpumask *cpu_mc_mask(int cpu)
+{
+ return cpu_coregroup_mask(cpu);
+}
+
static struct sched_domain_topology_level powerpc_topology[] = {
#ifdef CONFIG_SCHED_SMT
{ cpu_smt_mask, powerpc_smt_flags, SD_INIT_NAME(SMT) },
#endif
{ shared_cache_mask, powerpc_shared_cache_flags, SD_INIT_NAME(CACHE) },
+ { cpu_mc_mask, SD_INIT_NAME(MC) },
{ cpu_cpu_mask, SD_INIT_NAME(DIE) },
{ NULL, },
};
@@ -912,6 +938,10 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
GFP_KERNEL, cpu_to_node(cpu));
zalloc_cpumask_var_node(&per_cpu(cpu_core_map, cpu),
GFP_KERNEL, cpu_to_node(cpu));
+ if (has_coregroup_support())
+ zalloc_cpumask_var_node(&per_cpu(cpu_coregroup_map, cpu),
+ GFP_KERNEL, cpu_to_node(cpu));
+
#ifdef CONFIG_NEED_MULTIPLE_NODES
/*
* numa_node_id() works after this.
@@ -929,6 +959,9 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
cpumask_set_cpu(boot_cpuid, cpu_l2_cache_mask(boot_cpuid));
cpumask_set_cpu(boot_cpuid, cpu_core_mask(boot_cpuid));

+ if (has_coregroup_support())
+ cpumask_set_cpu(boot_cpuid, cpu_coregroup_mask(boot_cpuid));
+
init_big_cores();
if (has_big_cores) {
cpumask_set_cpu(boot_cpuid,
@@ -1220,6 +1253,8 @@ static void remove_cpu_from_masks(int cpu)
set_cpus_unrelated(cpu, i, cpu_sibling_mask);
if (has_big_cores)
set_cpus_unrelated(cpu, i, cpu_smallcore_mask);
+ if (has_coregroup_support())
+ set_cpus_unrelated(cpu, i, cpu_coregroup_mask);
}
}
#endif
@@ -1280,6 +1315,20 @@ static void add_cpu_to_masks(int cpu)
add_cpu_to_smallcore_masks(cpu);
update_mask_by_l2(cpu, cpu_l2_cache_mask);

+ if (has_coregroup_support()) {
+ int coregroup_id = cpu_to_coregroup_id(cpu);
+
+ cpumask_set_cpu(cpu, cpu_coregroup_mask(cpu));
+ for_each_cpu_and(i, cpu_online_mask, cpu_cpu_mask(cpu)) {
+ int fcpu = cpu_first_thread_sibling(i);
+
+ if (fcpu == first_thread)
+ set_cpus_related(cpu, i, cpu_coregroup_mask);
+ else if (coregroup_id == cpu_to_coregroup_id(i))
+ set_cpus_related(cpu, i, cpu_coregroup_mask);
+ }
+ }
+
if (pkg_id == -1) {
struct cpumask *(*mask)(int) = cpu_sibling_mask;

@@ -1374,9 +1423,12 @@ static void fixup_topology(void)
#ifdef CONFIG_SCHED_SMT
if (has_big_cores) {
pr_info("Big cores detected but using small core scheduling\n");
- powerpc_topology[0].mask = smallcore_smt_mask;
+ powerpc_topology[smt_idx].mask = smallcore_smt_mask;
}
#endif
+
+ if (!has_coregroup_support())
+ powerpc_topology[mc_idx].mask = powerpc_topology[cache_idx].mask;
}

void __init smp_cpus_done(unsigned int max_cpus)
diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index 51cb672f113b..0d57779e7942 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -1216,6 +1216,11 @@ int find_and_online_cpu_nid(int cpu)
return new_nid;
}

+int cpu_to_coregroup_id(int cpu)
+{
+ return cpu_to_core_id(cpu);
+}
+
static int topology_update_init(void)
{
topology_inited = 1;
--
2.18.2