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perf tools: Add perf_evsel__read_size function

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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>
This commit is contained in:
Jiri Olsa 2017-07-26 14:02:04 +02:00 committed by Arnaldo Carvalho de Melo
parent ee438ec8f3
commit de63403bfd
1 changed files with 28 additions and 1 deletions
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29
tools/perf/util/evsel.c
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@ -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;