From: Chun-Tse Shao Date: Thu, 11 Jun 2026 21:56:32 +0000 (-0700) Subject: perf stat: Fix false NMI watchdog warning in aggregation modes X-Git-Tag: v7.2-rc1~60^2~33 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=325aabebbbc0520f95db3974d46e13a081cf6c28;p=thirdparty%2Flinux.git perf stat: Fix false NMI watchdog warning in aggregation modes In aggregation modes (e.g. --per-socket, --per-die, etc.), a counter might not be scheduled or counted on specific aggregate groups if it was not assigned to the CPUs belonging to those groups. However, the printout() check triggers the "print_free_counters_hint" logic unconditionally for any supported counter with a missing count. This results in a false "Some events weren't counted. Try disabling the NMI watchdog" warning. Furthermore, the NMI watchdog only reserves performance counters on core PMUs. Uncore PMU events (e.g. CHA, IMC) are not affected by the NMI watchdog, but their failures also falsely triggered this warning. This warning was originally introduced in commit 02d492e5dcb72c00 ("perf stat: Issue a HW watchdog disable hint") To fix this, restrict setting of print_free_counters_hint to only trigger for core PMU events by checking counter->pmu and counter->pmu->is_core. Example before/after: $ perf stat -M lpm_miss_lat --metric-only --per-socket -a -- sleep 1 Before: Performance counter stats for 'system wide': ns lpm_miss_lat_rem ns lpm_miss_lat_loc S0 126 202.3 207.9 S1 126 231.9 259.3 1.006029831 seconds time elapsed Some events weren't counted. Try disabling the NMI watchdog: echo 0 > /proc/sys/kernel/nmi_watchdog perf stat ... echo 1 > /proc/sys/kernel/nmi_watchdog After: Performance counter stats for 'system wide': ns lpm_miss_lat_rem ns lpm_miss_lat_loc S0 126 202.3 207.9 S1 126 231.9 259.3 1.006029831 seconds time elapsed Assisted-by: Gemini:gemini-next Reviewed-by: Ian Rogers Signed-off-by: Chun-Tse Shao Cc: Namhyung Kim Signed-off-by: Arnaldo Carvalho de Melo --- diff --git a/tools/perf/util/stat-display.c b/tools/perf/util/stat-display.c index 2b69d238858cf..0a5750bb59fa3 100644 --- a/tools/perf/util/stat-display.c +++ b/tools/perf/util/stat-display.c @@ -821,9 +821,9 @@ static void printout(struct perf_stat_config *config, struct outstate *os, ok = false; if (counter->supported) { - if (!evlist__has_hybrid_pmus(counter->evlist)) { + if (!evlist__has_hybrid_pmus(counter->evlist) && + counter->pmu && counter->pmu->is_core) config->print_free_counters_hint = 1; - } } }