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Subject[PATCH 01/15] perf tools: Add perf_evsel__read_size function
Date
From: Jiri Olsa <jolsa@kernel.org>

Currently we use the size of struct perf_counts_values to read the
event, which prevents us to put any new member to the struct.

Adding perf_evsel__read_size to return size of the buffer needed for
event read.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20170726120206.9099-2-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/evsel.c | 29 ++++++++++++++++++++++++++++-
1 file changed, 28 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 450b5fadf8cb..4dd0fcc06db9 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -1261,15 +1261,42 @@ void perf_counts_values__scale(struct perf_counts_values *count,
*pscaled = scaled;
}

+static int perf_evsel__read_size(struct perf_evsel *evsel)
+{
+ u64 read_format = evsel->attr.read_format;
+ int entry = sizeof(u64); /* value */
+ int size = 0;
+ int nr = 1;
+
+ if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
+ size += sizeof(u64);
+
+ if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
+ size += sizeof(u64);
+
+ if (read_format & PERF_FORMAT_ID)
+ entry += sizeof(u64);
+
+ if (read_format & PERF_FORMAT_GROUP) {
+ nr = evsel->nr_members;
+ size += sizeof(u64);
+ }
+
+ size += entry * nr;
+ return size;
+}
+
int perf_evsel__read(struct perf_evsel *evsel, int cpu, int thread,
struct perf_counts_values *count)
{
+ size_t size = perf_evsel__read_size(evsel);
+
memset(count, 0, sizeof(*count));

if (FD(evsel, cpu, thread) < 0)
return -EINVAL;

- if (readn(FD(evsel, cpu, thread), count, sizeof(*count)) <= 0)
+ if (readn(FD(evsel, cpu, thread), count->values, size) <= 0)
return -errno;

return 0;
--
2.9.4
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