[PATCH v3 01/48] libperf: Add comments to perf_cpu_map.
From: Ian Rogers <irogers@google.com>
Date: 2021-12-30 07:20:41
Also in:
linux-perf-users, lkml
Subsystem:
performance events subsystem, the rest · Maintainers:
Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo, Namhyung Kim, Linus Torvalds
A particular observed problem is confusing the index with the CPU value, documentation should hopefully reduce this type of problem. Reviewed-by: James Clark <redacted> Signed-off-by: Ian Rogers <irogers@google.com> --- tools/lib/perf/include/internal/cpumap.h | 9 +++++++++ 1 file changed, 9 insertions(+)
diff --git a/tools/lib/perf/include/internal/cpumap.h b/tools/lib/perf/include/internal/cpumap.h
index 840d4032587b..4054169c12c5 100644
--- a/tools/lib/perf/include/internal/cpumap.h
+++ b/tools/lib/perf/include/internal/cpumap.h@@ -4,9 +4,18 @@ #include <linux/refcount.h> +/** + * A sized, reference counted, sorted array of integers representing CPU + * numbers. This is commonly used to capture which CPUs a PMU is associated + * with. The indices into the cpumap are frequently used as they avoid having + * gaps if CPU numbers were used. For events associated with a pid, rather than + * a CPU, a single dummy map with an entry of -1 is used. + */ struct perf_cpu_map { refcount_t refcnt; + /** Length of the map array. */ int nr; + /** The CPU values. */ int map[]; };
--
2.34.1.448.ga2b2bfdf31-goog
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