[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

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

[Namhyung Kim]

On Tue, Apr 07, 2026 at 01:38:43PM -0700, Chun-Tse Shao wrote:
> 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 */

It'd be great if we can share these string literals..


>  		};
>  		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);

... in here as well.

Thanks,
Namhyung


> +				}
> +				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
> 

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

[Namhyung Kim]

Hello,

On Tue, Apr 07, 2026 at 01:38:42PM -0700, Chun-Tse Shao wrote:
> 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;

Like sashiko said, I'm curious if it'd work well on 1-socket machine
which may have the same number of uncore IMC PMUs.

Zide, can you confirm?

Thanks,
Namhyung

>  	}
> -	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
> 

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

[Chen, Zide]

On 4/9/2026 9:39 PM, Namhyung Kim wrote:
> Hello,
> 
> On Tue, Apr 07, 2026 at 01:38:42PM -0700, Chun-Tse Shao wrote:
>> 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;
> 
> Like sashiko said, I'm curious if it'd work well on 1-socket machine
> which may have the same number of uncore IMC PMUs.
> 
> Zide, can you confirm?

On 1-socket, 1-die systems, the IMC controllers may be the same as on
multi-die systems. Theoretically, this could cause issues if NUMA is
enabled, but I am not aware of any platforms that support SNC on
single-die GNR/EMR SKUs.

I checked on a single-die GNR WS: SNC is not supported, so snc_nodes ==
1 and the cpumask adjustment is correctly skipped.

> 
> Thanks,
> Namhyung
> 
>>  	}
>> -	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
>>