overlay: Add graph for GPU power consumption

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 86 insertions, 0 deletions

diff --git a/overlay/power.c b/overlay/power.c
new file mode 100644
index 00000000..68470a2c
--- /dev/null
+++ b/overlay/power.c
@@ -0,0 +1,86 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <time.h>
+#include <errno.h>
+
+#include "power.h"
+
+/* XXX Is this exposed through RAPL? */
+
+int power_init(struct power *power)
+{
+	char buf[4096];
+	int fd, len;
+
+	memset(power, 0, sizeof(*power));
+
+	fd = open("/sys/kernel/debug/dri/0/i915_energy_uJ", 0);
+	if (fd < 0)
+		return power->error = errno;
+
+	len = read(fd, buf, sizeof(buf));
+	close(fd);
+
+	if (len < 0)
+		return power->error = errno;
+
+	return 0;
+}
+
+static uint64_t file_to_u64(const char *path)
+{
+	char buf[4096];
+	int fd, len;
+
+	fd = open(path, 0);
+	if (fd < 0)
+		return 0;
+
+	len = read(fd, buf, sizeof(buf)-1);
+	close(fd);
+
+	if (len < 0)
+		return 0;
+
+	buf[len] = '\0';
+
+	return strtoull(buf, 0, 0);
+}
+
+static uint64_t clock_ms_to_u64(void)
+{
+	struct timespec tv;
+
+	if (clock_gettime(CLOCK_MONOTONIC, &tv) < 0)
+		return 0;
+
+	return (uint64_t)tv.tv_sec * 1000 + tv.tv_nsec / 10000000;
+}
+
+int power_update(struct power *power)
+{
+	struct power_stat *s = &power->stat[power->count++&1];
+	struct power_stat *d = &power->stat[power->count&1];
+	uint64_t d_time;
+
+	if (power->error)
+		return power->error;
+
+	s->energy = file_to_u64("/sys/kernel/debug/dri/0/i915_energy_uJ");
+	s->timestamp = clock_ms_to_u64();
+	if (power->count == 1)
+		return EAGAIN;
+
+	d_time = s->timestamp - d->timestamp;
+	if (d_time < 1200) { /* HW sample rate seems to be stable ~1Hz */
+		power->count--;
+		return power->count <= 1 ? EAGAIN : 0;
+	}
+
+	power->power_mW = (s->energy - d->energy) / d_time;
+	power->new_sample = 1;
+	return 0;
+}