tools/perf/stat: Add event unit and scale support

This patch adds perf stat support for handling event units and
scales as exported by the kernel.

The kernel can export PMU events actual unit and scaling factor
via sysfs:

  $ ls -1 /sys/devices/power/events/energy-*
  /sys/devices/power/events/energy-cores
  /sys/devices/power/events/energy-cores.scale
  /sys/devices/power/events/energy-cores.unit
  /sys/devices/power/events/energy-pkg
  /sys/devices/power/events/energy-pkg.scale
  /sys/devices/power/events/energy-pkg.unit
  $ cat /sys/devices/power/events/energy-cores.scale
  2.3283064365386962890625e-10
  $ cat cat /sys/devices/power/events/energy-cores.unit
  Joules

This patch modifies the pmu event alias code to check
for the presence of the .unit and .scale files to load
the corresponding values. They are then used by perf stat
transparently:

   # perf stat -a -e power/energy-pkg/,power/energy-cores/,cycles -I 1000 sleep 1000
   #          time             counts   unit events
       1.000214717               3.07 Joules power/energy-pkg/         [100.00%]
       1.000214717               0.53 Joules power/energy-cores/
       1.000214717           12965028        cycles                    [100.00%]
       2.000749289               3.01 Joules power/energy-pkg/
       2.000749289               0.52 Joules power/energy-cores/
       2.000749289           15817043        cycles

When the event does not have an explicit unit exported by
the kernel, nothing is printed. In csv output mode, there
will be an empty field.

Special thanks to Jiri for providing the supporting code
in the parser to trigger reading of the scale and unit files.

Signed-off-by: Stephane Eranian <eranian@google.com>
Reviewed-by: Jiri Olsa <jolsa@redhat.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: zheng.z.yan@intel.com
Cc: bp@alien8.de
Cc: maria.n.dimakopoulou@gmail.com
Cc: acme@redhat.com
Link: http://lkml.kernel.org/r/1384275531-10892-3-git-send-email-eranian@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 134 insertions, 4 deletions

diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index c232d8dd410..56fc10a5e28 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -1,19 +1,23 @@
 #include <linux/list.h>
 #include <sys/types.h>
-#include <sys/stat.h>
 #include <unistd.h>
 #include <stdio.h>
 #include <dirent.h>
 #include "fs.h"
+#include <locale.h>
 #include "util.h"
 #include "pmu.h"
 #include "parse-events.h"
 #include "cpumap.h"
 
+#define UNIT_MAX_LEN	31 /* max length for event unit name */
+
 struct perf_pmu_alias {
 	char *name;
 	struct list_head terms;
 	struct list_head list;
+	char unit[UNIT_MAX_LEN+1];
+	double scale;
 };
 
 struct perf_pmu_format {
@@ -94,7 +98,80 @@ static int pmu_format(const char *name, struct list_head *format)
 	return 0;
 }
 
-static int perf_pmu__new_alias(struct list_head *list, char *name, FILE *file)
+static int perf_pmu__parse_scale(struct perf_pmu_alias *alias, char *dir, char *name)
+{
+	struct stat st;
+	ssize_t sret;
+	char scale[128];
+	int fd, ret = -1;
+	char path[PATH_MAX];
+	char *lc;
+
+	snprintf(path, PATH_MAX, "%s/%s.scale", dir, name);
+
+	fd = open(path, O_RDONLY);
+	if (fd == -1)
+		return -1;
+
+	if (fstat(fd, &st) < 0)
+		goto error;
+
+	sret = read(fd, scale, sizeof(scale)-1);
+	if (sret < 0)
+		goto error;
+
+	scale[sret] = '\0';
+	/*
+	 * save current locale
+	 */
+	lc = setlocale(LC_NUMERIC, NULL);
+
+	/*
+	 * force to C locale to ensure kernel
+	 * scale string is converted correctly.
+	 * kernel uses default C locale.
+	 */
+	setlocale(LC_NUMERIC, "C");
+
+	alias->scale = strtod(scale, NULL);
+
+	/* restore locale */
+	setlocale(LC_NUMERIC, lc);
+
+	ret = 0;
+error:
+	close(fd);
+	return ret;
+}
+
+static int perf_pmu__parse_unit(struct perf_pmu_alias *alias, char *dir, char *name)
+{
+	char path[PATH_MAX];
+	ssize_t sret;
+	int fd;
+
+	snprintf(path, PATH_MAX, "%s/%s.unit", dir, name);
+
+	fd = open(path, O_RDONLY);
+	if (fd == -1)
+		return -1;
+
+		sret = read(fd, alias->unit, UNIT_MAX_LEN);
+	if (sret < 0)
+		goto error;
+
+	close(fd);
+
+	alias->unit[sret] = '\0';
+
+	return 0;
+error:
+	close(fd);
+	alias->unit[0] = '\0';
+	return -1;
+}
+
+static int perf_pmu__new_alias(struct list_head *list, char *dir, char *name, FILE *file)
 {
 	struct perf_pmu_alias *alias;
 	char buf[256];
@@ -110,6 +187,9 @@ static int perf_pmu__new_alias(struct list_head *list, char *name, FILE *file)
 		return -ENOMEM;
 
 	INIT_LIST_HEAD(&alias->terms);
+	alias->scale = 1.0;
+	alias->unit[0] = '\0';
+
 	ret = parse_events_terms(&alias->terms, buf);
 	if (ret) {
 		free(alias);
@@ -117,7 +197,14 @@ static int perf_pmu__new_alias(struct list_head *list, char *name, FILE *file)
 	}
 
 	alias->name = strdup(name);
+	/*
+	 * load unit name and scale if available
+	 */
+	perf_pmu__parse_unit(alias, dir, name);
+	perf_pmu__parse_scale(alias, dir, name);
+
 	list_add_tail(&alias->list, list);
+
 	return 0;
 }
 
@@ -129,6 +216,7 @@ static int pmu_aliases_parse(char *dir, struct list_head *head)
 {
 	struct dirent *evt_ent;
 	DIR *event_dir;
+	size_t len;
 	int ret = 0;
 
 	event_dir = opendir(dir);
@@ -143,13 +231,24 @@ static int pmu_aliases_parse(char *dir, struct list_head *head)
 		if (!strcmp(name, ".") || !strcmp(name, ".."))
 			continue;
 
+		/*
+		 * skip .unit and .scale info files
+		 * parsed in perf_pmu__new_alias()
+		 */
+		len = strlen(name);
+		if (len > 5 && !strcmp(name + len - 5, ".unit"))
+			continue;
+		if (len > 6 && !strcmp(name + len - 6, ".scale"))
+			continue;
+
 		snprintf(path, PATH_MAX, "%s/%s", dir, name);
 
 		ret = -EINVAL;
 		file = fopen(path, "r");
 		if (!file)
 			break;
-		ret = perf_pmu__new_alias(head, name, file);
+
+		ret = perf_pmu__new_alias(head, dir, name, file);
 		fclose(file);
 	}
 
@@ -508,16 +607,42 @@ static struct perf_pmu_alias *pmu_find_alias(struct perf_pmu *pmu,
 	return NULL;
 }
 
+
+static int check_unit_scale(struct perf_pmu_alias *alias,
+			    char **unit, double *scale)
+{
+	/*
+	 * Only one term in event definition can
+	 * define unit and scale, fail if there's
+	 * more than one.
+	 */
+	if ((*unit && alias->unit) ||
+	    (*scale && alias->scale))
+		return -EINVAL;
+
+	if (alias->unit)
+		*unit = alias->unit;
+
+	if (alias->scale)
+		*scale = alias->scale;
+
+	return 0;
+}
+
 /*
  * Find alias in the terms list and replace it with the terms
  * defined for the alias
  */
-int perf_pmu__check_alias(struct perf_pmu *pmu, struct list_head *head_terms)
+int perf_pmu__check_alias(struct perf_pmu *pmu, struct list_head *head_terms,
+			  char **unit, double *scale)
 {
 	struct parse_events_term *term, *h;
 	struct perf_pmu_alias *alias;
 	int ret;
 
+	*unit   = NULL;
+	*scale  = 0;
+
 	list_for_each_entry_safe(term, h, head_terms, list) {
 		alias = pmu_find_alias(pmu, term);
 		if (!alias)
@@ -525,6 +650,11 @@ int perf_pmu__check_alias(struct perf_pmu *pmu, struct list_head *head_terms)
 		ret = pmu_alias_terms(alias, &term->list);
 		if (ret)
 			return ret;
+
+		ret = check_unit_scale(alias, unit, scale);
+		if (ret)
+			return ret;
+
 		list_del(&term->list);
 		free(term);
 	}