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

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

On 1/15/2026 2:03 AM, Chun-Tse Shao wrote:
> Hi Dapeng,
>
> I set the SNC2 config to {0, 0, 1, 1} because that is how my EMR
> testing machine shows with SNC2 enabled. If that is true, I wonder if
> the SNC2 map for GNR is still {1, 1, 0, 0}.

Ok, let me find a GNR to double check it. (Maybe next week, I have some
higher priority things on my hand in this week). Thanks.


>
> Thanks,
> CT
>
> On Tue, Jan 13, 2026 at 4:42 PM Mi, Dapeng <dapeng1.mi@linux.intel.com> wrote:
>>
>> 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
>>>>>