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[v3,01/48] libperf: Add comments to perf_cpu_map.

Message ID 20211230072030.302559-2-irogers@google.com (mailing list archive)
State New, archived
Headers show
Series Refactor perf cpumap | expand

Commit Message

Ian Rogers Dec. 30, 2021, 7:19 a.m. UTC 
A particular observed problem is confusing the index with the CPU value,
documentation should hopefully reduce this type of problem.

Reviewed-by: James Clark <james.clark@arm.com>
Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/lib/perf/include/internal/cpumap.h | 9 +++++++++
 1 file changed, 9 insertions(+)
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Patch

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[];
 };