[PATCH v5 1/2] perf pmu intel: Generalize SNC cpumask adjustment for multiple platforms

[PATCH v5 1/2] perf pmu intel: Generalize SNC cpumask adjustment for multiple platforms

[Chun-Tse Shao]

Prepare for supporting more Intel platforms with sub-NUMA clustering by
generalizing the GNR specific logic.

Signed-off-by: Chun-Tse Shao <ctshao@google.com>
---
v5:
  Split patch.

v4: lore.kernel.org/20260402205300.1953706-1-ctshao@google.com
  Rebase.

v3: lore.kernel.org/20260212223942.3832857-1-ctshao@google.com
  Fix a typo.

v2: lore.kernel.org/20260205232220.1980168-1-ctshao@google.com
  Split EMR and GNR in the SNC2 IMC cpu map.

v1: lore.kernel.org/20260108184430.1210223-1-ctshao@google.com

 tools/perf/arch/x86/util/pmu.c | 44 +++++++++++++++++++++-------------
 1 file changed, 27 insertions(+), 17 deletions(-)

diff --git a/tools/perf/arch/x86/util/pmu.c b/tools/perf/arch/x86/util/pmu.c
index 0661e0f0b02d..938be36ec0f7 100644
--- a/tools/perf/arch/x86/util/pmu.c
+++ b/tools/perf/arch/x86/util/pmu.c
@@ -23,20 +23,28 @@
 #include "util/env.h"
 #include "util/header.h"

-static bool x86__is_intel_graniterapids(void)
+static bool x86__is_snc_supported(void)
 {
-	static bool checked_if_graniterapids;
-	static bool is_graniterapids;
+	static bool checked_if_snc_supported;
+	static bool is_supported;

-	if (!checked_if_graniterapids) {
-		const char *graniterapids_cpuid = "GenuineIntel-6-A[DE]";
+	if (!checked_if_snc_supported) {
+
+		/* Graniterapids supports SNC configuration. */
+		static const char *const supported_cpuids[] = {
+			"GenuineIntel-6-A[DE]", /* Graniterapids */
+		};
 		char *cpuid = get_cpuid_str((struct perf_cpu){0});

-		is_graniterapids = cpuid && strcmp_cpuid_str(graniterapids_cpuid, cpuid) == 0;
+		for (size_t i = 0; i < ARRAY_SIZE(supported_cpuids); i++) {
+			is_supported = cpuid && strcmp_cpuid_str(supported_cpuids[i], cpuid) == 0;
+			if (is_supported)
+				break;
+		}
 		free(cpuid);
-		checked_if_graniterapids = true;
+		checked_if_snc_supported = true;
 	}
-	return is_graniterapids;
+	return is_supported;
 }

 static struct perf_cpu_map *read_sysfs_cpu_map(const char *sysfs_path)
@@ -133,8 +141,8 @@ static int uncore_imc_snc(struct perf_pmu *pmu)
 	// Compute the IMC SNC using lookup tables.
 	unsigned int imc_num;
 	int snc_nodes = snc_nodes_per_l3_cache();
-	const u8 snc2_map[] = {1, 1, 0, 0, 1, 1, 0, 0};
-	const u8 snc3_map[] = {1, 1, 0, 0, 2, 2, 1, 1, 0, 0, 2, 2};
+	const u8 snc2_map[] = {1, 1, 0, 0};
+	const u8 snc3_map[] = {1, 1, 0, 0, 2, 2};
 	const u8 *snc_map;
 	size_t snc_map_len;

@@ -157,11 +165,12 @@ static int uncore_imc_snc(struct perf_pmu *pmu)
 		pr_warning("Unexpected: unable to compute IMC number '%s'\n", pmu->name);
 		return 0;
 	}
-	if (imc_num >= snc_map_len) {
+	if (imc_num >= snc_map_len * perf_cpu_map__nr(pmu->cpus)) {
 		pr_warning("Unexpected IMC %d for SNC%d mapping\n", imc_num, snc_nodes);
 		return 0;
 	}
-	return snc_map[imc_num];
+
+	return snc_map[imc_num % snc_map_len];
 }

 static int uncore_cha_imc_compute_cpu_adjust(int pmu_snc)
@@ -201,7 +210,7 @@ static int uncore_cha_imc_compute_cpu_adjust(int pmu_snc)
 	return cpu_adjust[pmu_snc];
 }

-static void gnr_uncore_cha_imc_adjust_cpumask_for_snc(struct perf_pmu *pmu, bool cha)
+static void uncore_cha_imc_adjust_cpumask_for_snc(struct perf_pmu *pmu, bool cha)
 {
 	// With sub-NUMA clustering (SNC) there is a NUMA node per SNC in the
 	// topology. For example, a two socket graniterapids machine may be set
@@ -301,11 +310,12 @@ void perf_pmu__arch_init(struct perf_pmu *pmu)
 				pmu->mem_events = perf_mem_events_intel_aux;
 			else
 				pmu->mem_events = perf_mem_events_intel;
-		} else if (x86__is_intel_graniterapids()) {
+		} else if (x86__is_snc_supported()) {
 			if (strstarts(pmu->name, "uncore_cha_"))
-				gnr_uncore_cha_imc_adjust_cpumask_for_snc(pmu, /*cha=*/true);
-			else if (strstarts(pmu->name, "uncore_imc_"))
-				gnr_uncore_cha_imc_adjust_cpumask_for_snc(pmu, /*cha=*/false);
+				uncore_cha_imc_adjust_cpumask_for_snc(pmu, /*cha=*/true);
+			else if (strstarts(pmu->name, "uncore_imc_") &&
+				 !strstarts(pmu->name, "uncore_imc_free_running"))
+				uncore_cha_imc_adjust_cpumask_for_snc(pmu, /*cha=*/false);
 		}
 	}
 }
--
2.53.0.1213.gd9a14994de-goog

[PATCH v5 2/2] perf pmu intel: Adjust cpumaks for sub-NUMA clusters on Emeraldrapids

[Chun-Tse Shao]

Similar to GNR [1], Emeraldrapids supports sub-NUMA clusters as well.
Adjust cpumasks as the logic for GNR in [1].

Tested on Emeraldrapids with SNC2 enabled:
  $ perf stat --per-node -e 'UNC_CHA_CLOCKTICKS,UNC_M_CLOCKTICKS' -a -- sleep 1

   Performance counter stats for 'system wide':

  N0       30        72125876670      UNC_CHA_CLOCKTICKS
  N0        4         8815163648      UNC_M_CLOCKTICKS
  N1       30        72124958844      UNC_CHA_CLOCKTICKS
  N1        4         8815014974      UNC_M_CLOCKTICKS
  N2       30        72121049022      UNC_CHA_CLOCKTICKS
  N2        4         8814592626      UNC_M_CLOCKTICKS
  N3       30        72117133854      UNC_CHA_CLOCKTICKS
  N3        4         8814012840      UNC_M_CLOCKTICKS

         1.001574118 seconds time elapsed

[1] lore.kernel.org/20250515181417.491401-1-irogers@google.com

Reviewed-by: Zide Chen <zide.chen@intel.com>
Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Chun-Tse Shao <ctshao@google.com>
---
 tools/perf/arch/x86/util/pmu.c | 56 +++++++++++++++++++++++-----------
 1 file changed, 38 insertions(+), 18 deletions(-)

diff --git a/tools/perf/arch/x86/util/pmu.c b/tools/perf/arch/x86/util/pmu.c
index 938be36ec0f7..3743f5145505 100644
--- a/tools/perf/arch/x86/util/pmu.c
+++ b/tools/perf/arch/x86/util/pmu.c
@@ -30,8 +30,9 @@ static bool x86__is_snc_supported(void)
 
 	if (!checked_if_snc_supported) {
 
-		/* Graniterapids supports SNC configuration. */
+		/* Emeraldrapids Graniterapids support SNC configuration. */
 		static const char *const supported_cpuids[] = {
+			"GenuineIntel-6-CF", /* Emeraldrapids */
 			"GenuineIntel-6-A[DE]", /* Graniterapids */
 		};
 		char *cpuid = get_cpuid_str((struct perf_cpu){0});
@@ -141,23 +142,42 @@ static int uncore_imc_snc(struct perf_pmu *pmu)
 	// Compute the IMC SNC using lookup tables.
 	unsigned int imc_num;
 	int snc_nodes = snc_nodes_per_l3_cache();
-	const u8 snc2_map[] = {1, 1, 0, 0};
-	const u8 snc3_map[] = {1, 1, 0, 0, 2, 2};
-	const u8 *snc_map;
-	size_t snc_map_len;
-
-	switch (snc_nodes) {
-	case 2:
-		snc_map = snc2_map;
-		snc_map_len = ARRAY_SIZE(snc2_map);
-		break;
-	case 3:
-		snc_map = snc3_map;
-		snc_map_len = ARRAY_SIZE(snc3_map);
-		break;
-	default:
-		/* Error or no lookup support for SNC with >3 nodes. */
-		return 0;
+	char *cpuid;
+	static const u8 emr_snc2_map[] = { 0, 0, 1, 1 };
+	static const u8 gnr_snc2_map[] = { 1, 1, 0, 0 };
+	static const u8 snc3_map[] = { 1, 1, 0, 0, 2, 2 };
+	static const u8 *snc_map;
+	static size_t snc_map_len;
+
+	/* snc_map is not inited yet. We only look up once to avoid expensive operations. */
+	if (!snc_map) {
+		switch (snc_nodes) {
+		case 2:
+			cpuid = get_cpuid_str((struct perf_cpu){ 0 });
+			if (cpuid) {
+				if (strcmp_cpuid_str("GenuineIntel-6-CF", cpuid) == 0) {
+					snc_map = emr_snc2_map;
+					snc_map_len = ARRAY_SIZE(emr_snc2_map);
+				} else if (strcmp_cpuid_str("GenuineIntel-6-A[DE]", cpuid) == 0) {
+					snc_map = gnr_snc2_map;
+					snc_map_len = ARRAY_SIZE(gnr_snc2_map);
+				}
+				free(cpuid);
+			}
+			break;
+		case 3:
+			snc_map = snc3_map;
+			snc_map_len = ARRAY_SIZE(snc3_map);
+			break;
+		default:
+			/* Error or no lookup support for SNC with >3 nodes. */
+			return 0;
+		}
+
+		if (!snc_map) {
+			pr_warning("Unexpected: can not find snc map config");
+			return 0;
+		}
 	}
 
 	/* Compute SNC for PMU. */
-- 
2.53.0.1213.gd9a14994de-goog