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Message-ID: <76406086-7175-43ac-90bc-3b268186ebbc@linux.intel.com>
Date: Wed, 14 Jan 2026 08:42:50 +0800
From: "Mi, Dapeng" <dapeng1.mi@...ux.intel.com>
To: Chun-Tse Shao <ctshao@...gle.com>, Ian Rogers <irogers@...gle.com>
Cc: Thomas Falcon <thomas.falcon@...el.com>, linux-kernel@...r.kernel.org,
peterz@...radead.org, mingo@...hat.com, acme@...nel.org,
namhyung@...nel.org, mark.rutland@....com,
alexander.shishkin@...ux.intel.com, jolsa@...nel.org,
adrian.hunter@...el.com, james.clark@...aro.org, ravi.bangoria@....com,
linux-perf-users@...r.kernel.org
Subject: Re: [PATCH] perf pmu intel: Adjust cpumaks for sub-NUMA clusters on
Emeraldrapids
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@...gle.com> wrote:
>> On Thu, Jan 8, 2026 at 10:45 AM Chun-Tse Shao <ctshao@...gle.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@...gle.com
>>>
>>> Signed-off-by: Chun-Tse Shao <ctshao@...gle.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
>>>
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