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Message-ID: <CAJpZYjVREv324c7SXDK2m+Tb0FKXnWaAfYREetZTWZ05zo1HYw@mail.gmail.com>
Date: Wed, 14 Jan 2026 10:03:43 -0800
From: Chun-Tse Shao <ctshao@...gle.com>
To: "Mi, Dapeng" <dapeng1.mi@...ux.intel.com>
Cc: Ian Rogers <irogers@...gle.com>, 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
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}.
Thanks,
CT
On Tue, Jan 13, 2026 at 4:42 PM Mi, Dapeng <dapeng1.mi@...ux.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@...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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