From d6f751c7adadf305d90001e86943af65ac75ef8f Mon Sep 17 00:00:00 2001 From: Christian Melendez Date: Wed, 23 Sep 2026 15:51:40 +0200 Subject: [PATCH] perf stat: Document task-clock/cpu-clock in TIMINGS task-clock/cpu-clock appear in perf stat's own example output but were never explained in perf-stat.txt, unlike time elapsed/user/sys. This came up unanswered on the list in 2013 and 2015 without docs ever being added. Reviewed-by: Ian Rogers Signed-off-by: Christian Melendez Link: https://lore.kernel.org/all/arWi_dY4y15J2rqh@google.com ] [ Removed the :u modifier from the task-clock example, per Namhyung request ] Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/Documentation/perf-stat.txt | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/tools/perf/Documentation/perf-stat.txt b/tools/perf/Documentation/perf-stat.txt index f334aabdc809..8ea17da89976 100644 --- a/tools/perf/Documentation/perf-stat.txt +++ b/tools/perf/Documentation/perf-stat.txt @@ -621,6 +621,16 @@ user/system lands: Those times are the very same as displayed by the 'time' tool. +We also display a clock-based timing metric that depends on the +target being monitored: + + 83723.452481 task-clock (msec) # 1.004 CPUs utilized + +For a single task, task-clock reports a clock count specific to that +task. When the target is a CPU or the whole system (-a or -C), +cpu-clock is reported instead. cpu-clock is a high-resolution per-CPU +timer. See perf_event_open(2) for more details. + CSV FORMAT ---------- @@ -671,4 +681,4 @@ that can be used for parsing. SEE ALSO -------- -linkperf:perf-top[1], linkperf:perf-list[1] +linkperf:perf-top[1], linkperf:perf-list[1], perf_event_open(2)