[PATCH v1 2/5] perf, tools: Save event scaling factors in perf.data

[Andi Kleen <andi@firstfloor.org>]

From: Andi Kleen <ak@linux.intel.com>

To process metrics, perf script needs to know the scaling
factors reported by sysfs for events. Save the scaling factors
in the perf.data metadata in a new SCALE header.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
 tools/perf/Documentation/perf.data-file-format.txt |  8 +++
 tools/perf/util/header.c                           | 60 ++++++++++++++++++++++
 tools/perf/util/header.h                           |  1 +
 3 files changed, 69 insertions(+)

diff --git a/tools/perf/Documentation/perf.data-file-format.txt b/tools/perf/Documentation/perf.data-file-format.txt
index 15e8b48077ba..dc91d0578f46 100644
--- a/tools/perf/Documentation/perf.data-file-format.txt
+++ b/tools/perf/Documentation/perf.data-file-format.txt
@@ -261,6 +261,14 @@ struct {
 	struct perf_header_string map;
 }[number_of_cache_levels];
 
+	HEADER_SCALE = 21,
+
+Save scaling factor of events. One entry for each event in the same
+order as other events in the header.
+
+	u32 	nr;
+	double	scale[nr];
+
 	other bits are reserved and should ignored for now
 	HEADER_FEAT_BITS	= 256,
 
diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index 605bbd5404fb..4f1d23cfb9b0 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -2147,6 +2147,65 @@ static int process_cache(struct feat_fd *ff, void *data __maybe_unused)
 	return -1;
 }
 
+static int write_scale(struct feat_fd *ff, struct perf_evlist *evlist)
+{
+	u32 num;
+	struct perf_evsel *evsel;
+
+	num = 0;
+	evlist__for_each_entry (evlist, evsel)
+		num++;
+
+	if (do_write(ff, &num, sizeof num) < 0)
+		return -1;
+	evlist__for_each_entry (evlist, evsel) {
+		if (do_write(ff, &evsel->scale, sizeof(double)) < 0)
+			return -1;
+	}
+	return 0;
+}
+
+static void print_scale(struct feat_fd *ff, FILE *fp)
+{
+	struct perf_session *session;
+	struct perf_evsel *evsel;
+	int num = 0;
+
+	session = container_of(ff->ph, struct perf_session, header);
+
+	num = 0;
+	evlist__for_each_entry(session->evlist, evsel) {
+		fprintf(fp, "# event %d %s scale %f\n",
+			num++,
+			evsel->name,
+			evsel->scale);
+	}
+}
+
+static int process_scale(struct feat_fd *ff, void *data __maybe_unused)
+{
+	u32 cnt;
+	struct perf_evsel *evsel;
+	struct perf_session *session;
+
+	session = container_of(ff->ph, struct perf_session, header);
+	if (do_read_u32(ff, &cnt))
+		return -1;
+	evlist__for_each_entry(session->evlist, evsel) {
+		if (__do_read(ff, &evsel->scale, sizeof(double)))
+			return -1;
+		if (ff->ph->needs_swap)
+			mem_bswap_64(&evsel->scale, sizeof(double));
+		if (--cnt <= 0)
+			break;
+	}
+	if (cnt) {
+		pr_debug("missing scale descriptors\n");
+		return 1;
+	}
+	return 0;
+}
+
 struct feature_ops {
 	int (*write)(struct feat_fd *ff, struct perf_evlist *evlist);
 	void (*print)(struct feat_fd *ff, FILE *fp);
@@ -2204,6 +2263,7 @@ static const struct feature_ops feat_ops[HEADER_LAST_FEATURE] = {
 	FEAT_OPN(AUXTRACE,	auxtrace,	false),
 	FEAT_OPN(STAT,		stat,		false),
 	FEAT_OPN(CACHE,		cache,		true),
+	FEAT_OPN(SCALE,		scale,		true),
 };
 
 struct header_print_data {
diff --git a/tools/perf/util/header.h b/tools/perf/util/header.h
index f7a16ee527b8..d13d9520191f 100644
--- a/tools/perf/util/header.h
+++ b/tools/perf/util/header.h
@@ -33,6 +33,7 @@ enum {
 	HEADER_AUXTRACE,
 	HEADER_STAT,
 	HEADER_CACHE,
+	HEADER_SCALE,
 	HEADER_LAST_FEATURE,
 	HEADER_FEAT_BITS	= 256,
 };
-- 
2.13.6