Commit 9d6c0e58 authored by He Rongguang's avatar He Rongguang Committed by Shuah Khan
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cpupower: fix TSC MHz calculation 



Commit 'cpupower: Make TSC read per CPU for Mperf monitor' (c2adb187)
changes TSC counter reads 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.

/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: c2adb187 ("cpupower: Make TSC read per CPU for Mperf monitor")
Signed-off-by: default avatarHe Rongguang <herongguang@linux.alibaba.com>
Signed-off-by: default avatarShuah Khan <skhan@linuxfoundation.org>
parent 46fd8c70

tools/power/cpupower/utils/idle_monitor/mperf_monitor.c

+9 −6
Original line number Diff line number Diff line
@@ -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] = {

	{
@@ -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);

}