diff mbox series

cpupower: fix TSC MHz calculation for Mperf monitor

Message ID 269b8bb2-85b5-4cc9-9354-a1270f2eed35@linux.alibaba.com (mailing list archive)
State New
Delegated to: Shuah Khan
Headers show
Series cpupower: fix TSC MHz calculation for Mperf monitor | expand

Commit Message

He Rongguang Nov. 28, 2024, 9:50 a.m. UTC
Commit 'cpupower: Make TSC read per CPU for Mperf monitor' (c2adb1877b7)
changes TSC counter reads to per cpu, but left time diff global (from
start of all cpus to end of all cpus), thus diff(time) is too large for
a cpu's tsc counting, resulting in far less than acutal TSC_Mhz and thus
`cpupower monitor` showing far less than actual cpu realtime frequency.

Fix this by making timediff also per cpu.

/proc/cpuinfo shows frequency:
cat /proc/cpuinfo | egrep -e 'processor' -e 'MHz'
...
processor : 171
cpu MHz   : 4108.498
...

before fix (System 100% busy):
    | Mperf              || Idle_Stats
 CPU| C0   | Cx   | Freq  || POLL | C1   | C2
 171|  0.77| 99.23|  2279||  0.00|  0.00|  0.00

after fix (System 100% busy):
    | Mperf              || Idle_Stats
 CPU| C0   | Cx   | Freq  || POLL | C1   | C2
 171|  0.46| 99.54|  4095||  0.00|  0.00|  0.00

Fixes: c2adb1877b76f ("cpupower: Make TSC read per CPU for Mperf monitor")
Signed-off-by: He Rongguang <herongguang@linux.alibaba.com>
---
 .../cpupower/utils/idle_monitor/mperf_monitor.c   | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

 	{
@@ -174,7 +174,7 @@ static int mperf_get_count_percent(unsigned int id,
double *percent,
 		dprint("%s: TSC Ref - mperf_diff: %llu, tsc_diff: %llu\n",
 		       mperf_cstates[id].name, mperf_diff, tsc_diff);
 	} else if (max_freq_mode == MAX_FREQ_SYSFS) {
-		timediff = max_frequency * timespec_diff_us(time_start, time_end);
+		timediff = max_frequency * timespec_diff_us(time_start[cpu],
time_end[cpu]);
 		*percent = 100.0 * mperf_diff / timediff;
 		dprint("%s: MAXFREQ - mperf_diff: %llu, time_diff: %llu\n",
 		       mperf_cstates[id].name, mperf_diff, timediff);
@@ -207,7 +207,7 @@ static int mperf_get_count_freq(unsigned int id,
unsigned long long *count,
 	if (max_freq_mode == MAX_FREQ_TSC_REF) {
 		/* Calculate max_freq from TSC count */
 		tsc_diff = tsc_at_measure_end[cpu] - tsc_at_measure_start[cpu];
-		time_diff = timespec_diff_us(time_start, time_end);
+		time_diff = timespec_diff_us(time_start[cpu], time_end[cpu]);
 		max_frequency = tsc_diff / time_diff;
 	}

@@ -226,9 +226,8 @@ static int mperf_start(void)
 {
 	int cpu;

-	clock_gettime(CLOCK_REALTIME, &time_start);
-
 	for (cpu = 0; cpu < cpu_count; cpu++) {
+		clock_gettime(CLOCK_REALTIME, &time_start[cpu]);
 		mperf_get_tsc(&tsc_at_measure_start[cpu]);
 		mperf_init_stats(cpu);
 	}
@@ -243,9 +242,9 @@ static int mperf_stop(void)
 	for (cpu = 0; cpu < cpu_count; cpu++) {
 		mperf_measure_stats(cpu);
 		mperf_get_tsc(&tsc_at_measure_end[cpu]);
+		clock_gettime(CLOCK_REALTIME, &time_end[cpu]);
 	}

-	clock_gettime(CLOCK_REALTIME, &time_end);
 	return 0;
 }

@@ -349,6 +348,8 @@ struct cpuidle_monitor *mperf_register(void)
 	aperf_current_count = calloc(cpu_count, sizeof(unsigned long long));
 	tsc_at_measure_start = calloc(cpu_count, sizeof(unsigned long long));
 	tsc_at_measure_end = calloc(cpu_count, sizeof(unsigned long long));
+	time_start = calloc(cpu_count, sizeof(struct timespec));
+	time_end = calloc(cpu_count, sizeof(struct timespec));
 	mperf_monitor.name_len = strlen(mperf_monitor.name);
 	return &mperf_monitor;
 }
@@ -361,6 +362,8 @@ void mperf_unregister(void)
 	free(aperf_current_count);
 	free(tsc_at_measure_start);
 	free(tsc_at_measure_end);
+	free(time_start);
+	free(time_end);
 	free(is_valid);
 }
diff mbox series

Patch

diff --git a/tools/power/cpupower/utils/idle_monitor/mperf_monitor.c
b/tools/power/cpupower/utils/idle_monitor/mperf_monitor.c
index ae6af354a81d..08a399b0be28 100644
--- a/tools/power/cpupower/utils/idle_monitor/mperf_monitor.c
+++ b/tools/power/cpupower/utils/idle_monitor/mperf_monitor.c
@@ -33,7 +33,7 @@  static int mperf_get_count_percent(unsigned int
self_id, double *percent,
 				   unsigned int cpu);
 static int mperf_get_count_freq(unsigned int id, unsigned long long *count,
 				unsigned int cpu);
-static struct timespec time_start, time_end;
+static struct timespec *time_start, *time_end;

 static cstate_t mperf_cstates[MPERF_CSTATE_COUNT] = {