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

Chun-Tse Shao
2026-04-07T20:39:38Z

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