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

["Mi, Dapeng" <dapeng1.mi@linux.intel.com>]

On 1/14/2026 2:06 AM, Chun-Tse Shao wrote:
> Ping.
>
> Thanks for your comment, Ian. To Intel team, can we get confirmation
> of the GNR SNR2 configuration?

It seems you missed Ian's comments. 

I have same question with Ian, the snc map for uncore IMC is changed. It
may not change the total count of uncore_imc events, but it would change
the count of the uncore_imc events for a specific SNC node. What's the
reason you did the change?

I have no GNR/EMR on my hand, I can't check how the SNC nodes are mapped on
these 2 machines.


>
> -CT
>
> On Thu, Jan 8, 2026 at 11:19 AM Ian Rogers <irogers@google.com> wrote:
>> On Thu, Jan 8, 2026 at 10:45 AM Chun-Tse Shao <ctshao@google.com> 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
>>>
>>> Signed-off-by: Chun-Tse Shao <ctshao@google.com>
>>> ---
>>>  tools/perf/arch/x86/util/pmu.c | 45 +++++++++++++++++++++-------------
>>>  1 file changed, 28 insertions(+), 17 deletions(-)
>>>
>>> diff --git a/tools/perf/arch/x86/util/pmu.c b/tools/perf/arch/x86/util/pmu.c
>>> index a3f96221758d..fad68a0f7b5d 100644
>>> --- a/tools/perf/arch/x86/util/pmu.c
>>> +++ b/tools/perf/arch/x86/util/pmu.c
>>> @@ -22,20 +22,29 @@
>>>  #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) {
>>> +
>>> +               /* Emeraldrapids and 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});
>>>
>>> -               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 checked_if_snc_supported;
>>>  }
>>>
>>>  static struct perf_cpu_map *read_sysfs_cpu_map(const char *sysfs_path)
>>> @@ -64,6 +73,7 @@ static int snc_nodes_per_l3_cache(void)
>>>                         read_sysfs_cpu_map("devices/system/cpu/cpu0/cache/index3/shared_cpu_list");
>>>
>>>                 snc_nodes = perf_cpu_map__nr(cache_cpus) / perf_cpu_map__nr(node_cpus);
>>> +
>>>                 perf_cpu_map__put(cache_cpus);
>>>                 perf_cpu_map__put(node_cpus);
>>>                 checked_snc = true;
>>> @@ -137,8 +147,8 @@ 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[] = {0, 0, 1, 1};
>> Does this alter the behavior on GNR? ie 1,1,0,0 vs 0,0,1,1.
>>
>> Thanks,
>> Ian
>>
>>> +       const u8 snc3_map[] = {1, 1, 0, 0, 2, 2};
>>>         const u8 *snc_map;
>>>         size_t snc_map_len;
>>>
>>> @@ -161,11 +171,11 @@ 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)
>>> @@ -205,7 +215,7 @@ 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
>>> @@ -304,11 +314,12 @@ 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 (starts_with(pmu->name, "uncore_cha_"))
>>> -                               gnr_uncore_cha_imc_adjust_cpumask_for_snc(pmu, /*cha=*/true);
>>> -                       else if (starts_with(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 (starts_with(pmu->name, "uncore_imc_") &&
>>> +                                !starts_with(pmu->name, "uncore_imc_free_running"))
>>> +                               uncore_cha_imc_adjust_cpumask_for_snc(pmu, /*cha=*/false);
>>>                 }
>>>         }
>>>  }
>>> --
>>> 2.52.0.457.g6b5491de43-goog
>>>