From 2dfc818b35cbea59188cc86e86e0a0efce2b0dbe Mon Sep 17 00:00:00 2001 From: Thomas Renninger Date: Fri, 12 Aug 2011 01:11:35 +0200 Subject: cpupower: mperf monitor - Use TSC to calculate max frequency if possible Which makes the implementation independent from cpufreq drivers. Therefore this would also work on a Xen kernel where the hypervisor is doing frequency switching and idle entering. Signed-off-by: Thomas Renninger Signed-off-by: Dominik Brodowski --- tools/power/cpupower/Makefile | 2 +- .../cpupower/utils/idle_monitor/mperf_monitor.c | 177 +++++++++++++++------ 2 files changed, 131 insertions(+), 48 deletions(-) (limited to 'tools/power/cpupower') diff --git a/tools/power/cpupower/Makefile b/tools/power/cpupower/Makefile index 94c2cf0..11521d2 100644 --- a/tools/power/cpupower/Makefile +++ b/tools/power/cpupower/Makefile @@ -24,7 +24,7 @@ # Set the following to `true' to make a unstripped, unoptimized # binary. Leave this set to `false' for production use. -DEBUG ?= false +DEBUG ?= true # make the build silent. Set this to something else to make it noisy again. V ?= false diff --git a/tools/power/cpupower/utils/idle_monitor/mperf_monitor.c b/tools/power/cpupower/utils/idle_monitor/mperf_monitor.c index 63ca87a..5650ab5 100644 --- a/tools/power/cpupower/utils/idle_monitor/mperf_monitor.c +++ b/tools/power/cpupower/utils/idle_monitor/mperf_monitor.c @@ -22,12 +22,15 @@ #define MSR_TSC 0x10 +#define MSR_AMD_HWCR 0xc0010015 + enum mperf_id { C0 = 0, Cx, AVG_FREQ, MPERF_CSTATE_COUNT }; 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 cstate_t mperf_cstates[MPERF_CSTATE_COUNT] = { { @@ -54,19 +57,33 @@ static cstate_t mperf_cstates[MPERF_CSTATE_COUNT] = { }, }; +enum MAX_FREQ_MODE { MAX_FREQ_SYSFS, MAX_FREQ_TSC_REF }; +static int max_freq_mode; +/* + * The max frequency mperf is ticking at (in C0), either retrieved via: + * 1) calculated after measurements if we know TSC ticks at mperf/P0 frequency + * 2) cpufreq /sys/devices/.../cpu0/cpufreq/cpuinfo_max_freq at init time + * 1. Is preferred as it also works without cpufreq subsystem (e.g. on Xen) + */ +static unsigned long max_frequency; + static unsigned long long tsc_at_measure_start; static unsigned long long tsc_at_measure_end; -static unsigned long max_frequency; static unsigned long long *mperf_previous_count; static unsigned long long *aperf_previous_count; static unsigned long long *mperf_current_count; static unsigned long long *aperf_current_count; + /* valid flag for all CPUs. If a MSR read failed it will be zero */ static int *is_valid; static int mperf_get_tsc(unsigned long long *tsc) { - return read_msr(0, MSR_TSC, tsc); + int ret; + ret = read_msr(0, MSR_TSC, tsc); + if (ret) + dprint("Reading TSC MSR failed, returning %llu\n", *tsc); + return ret; } static int mperf_init_stats(unsigned int cpu) @@ -97,36 +114,11 @@ static int mperf_measure_stats(unsigned int cpu) return 0; } -/* - * get_average_perf() - * - * Returns the average performance (also considers boosted frequencies) - * - * Input: - * aperf_diff: Difference of the aperf register over a time period - * mperf_diff: Difference of the mperf register over the same time period - * max_freq: Maximum frequency (P0) - * - * Returns: - * Average performance over the time period - */ -static unsigned long get_average_perf(unsigned long long aperf_diff, - unsigned long long mperf_diff) -{ - unsigned int perf_percent = 0; - if (((unsigned long)(-1) / 100) < aperf_diff) { - int shift_count = 7; - aperf_diff >>= shift_count; - mperf_diff >>= shift_count; - } - perf_percent = (aperf_diff * 100) / mperf_diff; - return (max_frequency * perf_percent) / 100; -} - static int mperf_get_count_percent(unsigned int id, double *percent, unsigned int cpu) { unsigned long long aperf_diff, mperf_diff, tsc_diff; + unsigned long long timediff; if (!is_valid[cpu]) return -1; @@ -136,11 +128,19 @@ static int mperf_get_count_percent(unsigned int id, double *percent, mperf_diff = mperf_current_count[cpu] - mperf_previous_count[cpu]; aperf_diff = aperf_current_count[cpu] - aperf_previous_count[cpu]; - tsc_diff = tsc_at_measure_end - tsc_at_measure_start; - *percent = 100.0 * mperf_diff / tsc_diff; - dprint("%s: mperf_diff: %llu, tsc_diff: %llu\n", - mperf_cstates[id].name, mperf_diff, tsc_diff); + if (max_freq_mode == MAX_FREQ_TSC_REF) { + tsc_diff = tsc_at_measure_end - tsc_at_measure_start; + *percent = 100.0 * mperf_diff / tsc_diff; + 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 = timespec_diff_us(time_start, time_end); + *percent = 100.0 * mperf_diff / timediff; + dprint("%s: MAXFREQ - mperf_diff: %llu, time_diff: %llu\n", + mperf_cstates[id].name, mperf_diff, timediff); + } else + return -1; if (id == Cx) *percent = 100.0 - *percent; @@ -154,7 +154,7 @@ static int mperf_get_count_percent(unsigned int id, double *percent, static int mperf_get_count_freq(unsigned int id, unsigned long long *count, unsigned int cpu) { - unsigned long long aperf_diff, mperf_diff; + unsigned long long aperf_diff, mperf_diff, time_diff, tsc_diff; if (id != AVG_FREQ) return 1; @@ -165,11 +165,21 @@ static int mperf_get_count_freq(unsigned int id, unsigned long long *count, mperf_diff = mperf_current_count[cpu] - mperf_previous_count[cpu]; aperf_diff = aperf_current_count[cpu] - aperf_previous_count[cpu]; - /* Return MHz for now, might want to return KHz if column width is more - generic */ - *count = get_average_perf(aperf_diff, mperf_diff) / 1000; - dprint("%s: %llu\n", mperf_cstates[id].name, *count); + if (max_freq_mode == MAX_FREQ_TSC_REF) { + /* Calculate max_freq from TSC count */ + tsc_diff = tsc_at_measure_end - tsc_at_measure_start; + time_diff = timespec_diff_us(time_start, time_end); + max_frequency = tsc_diff / time_diff; + } + *count = max_frequency * ((double)aperf_diff / mperf_diff); + dprint("%s: Average freq based on %s maximum frequency:\n", + mperf_cstates[id].name, + (max_freq_mode == MAX_FREQ_TSC_REF) ? "TSC calculated" : "sysfs read"); + dprint("%max_frequency: %lu", max_frequency); + dprint("aperf_diff: %llu\n", aperf_diff); + dprint("mperf_diff: %llu\n", mperf_diff); + dprint("avg freq: %llu\n", *count); return 0; } @@ -178,6 +188,7 @@ static int mperf_start(void) int cpu; unsigned long long dbg; + clock_gettime(CLOCK_REALTIME, &time_start); mperf_get_tsc(&tsc_at_measure_start); for (cpu = 0; cpu < cpu_count; cpu++) @@ -193,32 +204,104 @@ static int mperf_stop(void) unsigned long long dbg; int cpu; - mperf_get_tsc(&tsc_at_measure_end); - for (cpu = 0; cpu < cpu_count; cpu++) mperf_measure_stats(cpu); + mperf_get_tsc(&tsc_at_measure_end); + clock_gettime(CLOCK_REALTIME, &time_end); + mperf_get_tsc(&dbg); dprint("TSC diff: %llu\n", dbg - tsc_at_measure_end); return 0; } -struct cpuidle_monitor mperf_monitor; - -struct cpuidle_monitor *mperf_register(void) +/* + * Mperf register is defined to tick at P0 (maximum) frequency + * + * Instead of reading out P0 which can be tricky to read out from HW, + * we use TSC counter if it reliably ticks at P0/mperf frequency. + * + * Still try to fall back to: + * /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq + * on older Intel HW without invariant TSC feature. + * Or on AMD machines where TSC does not tick at P0 (do not exist yet, but + * it's still double checked (MSR_AMD_HWCR)). + * + * On these machines the user would still get useful mperf + * stats when acpi-cpufreq driver is loaded. + */ +static int init_maxfreq_mode(void) { + int ret; + unsigned long long hwcr; unsigned long min; - if (!(cpupower_cpu_info.caps & CPUPOWER_CAP_APERF)) - return NULL; - - /* Assume min/max all the same on all cores */ + if (!cpupower_cpu_info.caps & CPUPOWER_CAP_INV_TSC) + goto use_sysfs; + + if (cpupower_cpu_info.vendor == X86_VENDOR_AMD) { + /* MSR_AMD_HWCR tells us whether TSC runs at P0/mperf + * freq. + * A test whether hwcr is accessable/available would be: + * (cpupower_cpu_info.family > 0x10 || + * cpupower_cpu_info.family == 0x10 && + * cpupower_cpu_info.model >= 0x2)) + * This should be the case for all aperf/mperf + * capable AMD machines and is therefore safe to test here. + * Compare with Linus kernel git commit: acf01734b1747b1ec4 + */ + ret = read_msr(0, MSR_AMD_HWCR, &hwcr); + /* + * If the MSR read failed, assume a Xen system that did + * not explicitly provide access to it and assume TSC works + */ + if (ret != 0) { + dprint("TSC read 0x%x failed - assume TSC working\n", + MSR_AMD_HWCR); + return 0; + } else if (1 & (hwcr >> 24)) { + max_freq_mode = MAX_FREQ_TSC_REF; + return 0; + } else { /* Use sysfs max frequency if available */ } + } else if (cpupower_cpu_info.vendor == X86_VENDOR_INTEL) { + /* + * On Intel we assume mperf (in C0) is ticking at same + * rate than TSC + */ + max_freq_mode = MAX_FREQ_TSC_REF; + return 0; + } +use_sysfs: if (cpufreq_get_hardware_limits(0, &min, &max_frequency)) { dprint("Cannot retrieve max freq from cpufreq kernel " "subsystem\n"); - return NULL; + return -1; } + max_freq_mode = MAX_FREQ_SYSFS; + return 0; +} + +/* + * This monitor provides: + * + * 1) Average frequency a CPU resided in + * This always works if the CPU has aperf/mperf capabilities + * + * 2) C0 and Cx (any sleep state) time a CPU resided in + * Works if mperf timer stops ticking in sleep states which + * seem to be the case on all current HW. + * Both is directly retrieved from HW registers and is independent + * from kernel statistics. + */ +struct cpuidle_monitor mperf_monitor; +struct cpuidle_monitor *mperf_register(void) +{ + if (!(cpupower_cpu_info.caps & CPUPOWER_CAP_APERF)) + return NULL; + + if (init_maxfreq_mode()) + return NULL; /* Free this at program termination */ is_valid = calloc(cpu_count, sizeof(int)); -- cgit v1.1