[igt-dev] [PATCH i-g-t 2/7] lib: Add GPU power measurement

[Chris Wilson]

Read the RAPL power metrics courtesy of perf. Or your local HW
equivalent?

v2: uselocale()

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 lib/Makefile.sources |   2 +
 lib/igt_gpu_power.c  | 114 +++++++++++++++++++++++++++++++++++++++++++
 lib/igt_gpu_power.h  |  59 ++++++++++++++++++++++
 lib/meson.build      |   2 +
 4 files changed, 177 insertions(+)
 create mode 100644 lib/igt_gpu_power.c
 create mode 100644 lib/igt_gpu_power.h

diff --git a/lib/Makefile.sources b/lib/Makefile.sources
index 9711fef34..8763753b0 100644
--- a/lib/Makefile.sources
+++ b/lib/Makefile.sources
@@ -24,6 +24,8 @@ lib_source_list =	 	\
 	igt_color_encoding.c	\
 	igt_color_encoding.h	\
 	igt_edid_template.h	\
+	igt_gpu_power.c		\
+	igt_gpu_power.h		\
 	igt_gt.c		\
 	igt_gt.h		\
 	igt_gvt.c		\
diff --git a/lib/igt_gpu_power.c b/lib/igt_gpu_power.c
new file mode 100644
index 000000000..a4e3c1420
--- /dev/null
+++ b/lib/igt_gpu_power.c
@@ -0,0 +1,114 @@
+#include <ctype.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <locale.h>
+#include <math.h>
+#include <unistd.h>
+
+#include "igt_gpu_power.h"
+#include "igt_perf.h"
+
+static int filename_to_buf(const char *filename, char *buf, unsigned int sz)
+{
+	int fd;
+	ssize_t ret;
+
+	fd = open(filename, O_RDONLY);
+	if (fd < 0)
+		return -1;
+
+	ret = read(fd, buf, sz - 1);
+	close(fd);
+	if (ret < 1)
+		return -1;
+
+	buf[ret] = '\0';
+
+	return 0;
+}
+
+static uint64_t filename_to_u64(const char *filename, int base)
+{
+	char buf[64], *b;
+
+	if (filename_to_buf(filename, buf, sizeof(buf)))
+		return 0;
+
+	/*
+	 * Handle both single integer and key=value formats by skipping
+	 * leading non-digits.
+	 */
+	b = buf;
+	while (*b && !isdigit(*b))
+		b++;
+
+	return strtoull(b, NULL, base);
+}
+
+static double filename_to_double(const char *filename)
+{
+	locale_t locale, oldlocale;
+	char buf[80];
+	double v;
+
+	if (filename_to_buf(filename, buf, sizeof(buf)))
+		return 0;
+
+	/* Replace user environment with plain C to match kernel format */
+	locale = newlocale(LC_ALL, "C", 0);
+	oldlocale = uselocale(locale);
+
+	v = strtod(buf, NULL);
+
+	uselocale(oldlocale);
+	freelocale(locale);
+
+	return v;
+}
+
+static uint64_t rapl_type_id(void)
+{
+	return filename_to_u64("/sys/devices/power/type", 10);
+}
+
+static uint64_t rapl_gpu_power(void)
+{
+	return filename_to_u64("/sys/devices/power/events/energy-gpu", 0);
+}
+
+static double rapl_gpu_power_scale(void)
+{
+	return filename_to_double("/sys/devices/power/events/energy-gpu.scale");
+}
+
+int gpu_power_open(struct gpu_power *power)
+{
+	power->fd = igt_perf_open(rapl_type_id(), rapl_gpu_power());
+	if (power->fd < 0) {
+		power->fd = -errno;
+		goto err;
+	}
+
+	power->scale = rapl_gpu_power_scale();
+	if (isnan(power->scale) || !power->scale) {
+		close(power->fd);
+		goto err;
+	}
+	power->scale *= 1e9;
+
+	return 0;
+
+err:
+	errno = 0;
+	return power->fd;
+}
+
+bool gpu_power_read(struct gpu_power *power, struct gpu_power_sample *s)
+{
+	return read(power->fd, s, sizeof(*s)) == sizeof(*s);
+}
+
+void gpu_power_close(struct gpu_power *power)
+{
+	close(power->fd);
+}
diff --git a/lib/igt_gpu_power.h b/lib/igt_gpu_power.h
new file mode 100644
index 000000000..4e1b747c0
--- /dev/null
+++ b/lib/igt_gpu_power.h
@@ -0,0 +1,59 @@
+/*
+ * Copyright © 2019 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ */
+
+#ifndef IGT_GPU_POWER_H
+#define IGT_GPU_POWER_H
+
+#include <stdbool.h>
+#include <stdint.h>
+
+struct gpu_power {
+	int fd;
+	double scale;
+};
+
+struct gpu_power_sample {
+	uint64_t energy;
+	uint64_t time;
+};
+
+int gpu_power_open(struct gpu_power *power);
+bool gpu_power_read(struct gpu_power *power, struct gpu_power_sample *s);
+void gpu_power_close(struct gpu_power *power);
+
+static inline double gpu_power_J(const struct gpu_power *p,
+				 const struct gpu_power_sample *t0,
+				 const struct gpu_power_sample *t1)
+{
+	return (t1->energy - t0->energy) * p->scale * 1e-9;
+}
+
+static inline double gpu_power_W(const struct gpu_power *p,
+				 const struct gpu_power_sample *t0,
+				 const struct gpu_power_sample *t1)
+{
+	return (t1->energy - t0->energy) * p->scale / (t1->time - t0->time);
+}
+
+#endif /* IGT_GPU_POWER_H */
diff --git a/lib/meson.build b/lib/meson.build
index dd36f8180..63279ae30 100644
--- a/lib/meson.build
+++ b/lib/meson.build
@@ -8,9 +8,11 @@ lib_sources = [
 	'igt_debugfs.c',
 	'igt_device.c',
 	'igt_aux.c',
+	'igt_gpu_power.c',
 	'igt_gt.c',
 	'igt_gvt.c',
 	'igt_matrix.c',
+	'igt_perf.c',
 	'igt_primes.c',
 	'igt_rand.c',
 	'igt_stats.c',
-- 
2.20.1