Re: [igt-dev] [PATCH i-g-t 02/24] lib: Add GPU power measurement

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 22/03/2019 09:21, Chris Wilson wrote:
> Read the RAPL power metrics courtesy of perf. Or your local HW
> equivalent?
> 
> v2: uselocale()
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>   lib/Makefile.am      |   1 +
>   lib/Makefile.sources |   2 +
>   lib/igt_gpu_power.c  | 114 +++++++++++++++++++++++++++++++++++++++++++
>   lib/igt_gpu_power.h  |  59 ++++++++++++++++++++++
>   lib/meson.build      |   2 +
>   5 files changed, 178 insertions(+)
>   create mode 100644 lib/igt_gpu_power.c
>   create mode 100644 lib/igt_gpu_power.h
> 
> diff --git a/lib/Makefile.am b/lib/Makefile.am
> index 3e6a7fdba..62e8bda73 100644
> --- a/lib/Makefile.am
> +++ b/lib/Makefile.am
> @@ -84,4 +84,5 @@ libintel_tools_la_LIBADD = \
>   	$(LIBUDEV_LIBS) \
>   	$(PIXMAN_LIBS) \
>   	$(GLIB_LIBS) \
> +	libigt_perf.la \
>   	-lm
> diff --git a/lib/Makefile.sources b/lib/Makefile.sources
> index cf2720981..e00347f94 100644
> --- a/lib/Makefile.sources
> +++ b/lib/Makefile.sources
> @@ -26,6 +26,8 @@ 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;
> +}

Hey you know what our guidelines for introducing a 3rd copy of something 
are. ;)

Maybe it would be fair game to stuff these helpers to igt_perf.la - 
since both overlay and intel_gpu_gpu link with it already and it is 
about interfacing with perf after all.

There are some small differences between the functions here and in 
intel_gpu_top, someone is right or wrong, or at least more right?

> +
> +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;

Scale has no unit so I think this would go better into gpu_power_W. 
Would avoid * 1e9 * 1e-9 in gpu_power_J as well.

> +
> +	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 0eb5585d7..89de06e69 100644
> --- a/lib/meson.build
> +++ b/lib/meson.build
> @@ -9,9 +9,11 @@ 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',
> 

Regards,

Tvrtko
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