perf evlist: Introduce id_hdr_size method out of perf_session

We will need this when not using perf_session in cases like 'perf top'
and strace where no perf.data file is created nor consumed.

Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-za923wjc41q5xot5vrhuhj3j@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 32 insertions, 0 deletions

diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 81237dcde1fd..d44e3df13a8f 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -625,6 +625,38 @@ u64 perf_evlist__sample_type(const struct perf_evlist *evlist)
         return first->attr.sample_type;
 }
 
+u16 perf_evlist__id_hdr_size(const struct perf_evlist *evlist)
+{
+        struct perf_evsel *first;
+        struct perf_sample *data;
+        u64 sample_type;
+        u16 size = 0;
+
+        first = list_entry(evlist->entries.next, struct perf_evsel, node);
+
+        if (!first->attr.sample_id_all)
+                goto out;
+
+        sample_type = first->attr.sample_type;
+
+        if (sample_type & PERF_SAMPLE_TID)
+                size += sizeof(data->tid) * 2;
+
+       if (sample_type & PERF_SAMPLE_TIME)
+                size += sizeof(data->time);
+
+        if (sample_type & PERF_SAMPLE_ID)
+                size += sizeof(data->id);
+
+        if (sample_type & PERF_SAMPLE_STREAM_ID)
+                size += sizeof(data->stream_id);
+
+        if (sample_type & PERF_SAMPLE_CPU)
+                size += sizeof(data->cpu) * 2;
+out:
+        return size;
+}
+
 bool perf_evlist__valid_sample_id_all(const struct perf_evlist *evlist)
 {
         struct perf_evsel *pos, *first;