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

   1 /*
   2  *  (C) 2010,2011       Thomas Renninger <trenn@suse.de>, Novell Inc.
   3  *
   4  *  Licensed under the terms of the GNU GPL License version 2.
   5  */
   6
   7 #if defined(__i386__) || defined(__x86_64__)
   8
   9 #include <stdio.h>
  10 #include <stdint.h>
  11 #include <stdlib.h>
  12 #include <string.h>
  13 #include <limits.h>
  14
  15 #include <cpufreq.h>
  16
  17 #include "helpers/helpers.h"
  18 #include "idle_monitor/cpupower-monitor.h"
  19
  20 #define MSR_APERF       0xE8
  21 #define MSR_MPERF       0xE7
  22
  23 #define MSR_TSC 0x10
  24
  25 #define MSR_AMD_HWCR 0xc0010015
  26
  27 enum mperf_id { C0 = 0, Cx, AVG_FREQ, MPERF_CSTATE_COUNT };
  28
  29 static int mperf_get_count_percent(unsigned int self_id, double *percent,
  30                                    unsigned int cpu);
  31 static int mperf_get_count_freq(unsigned int id, unsigned long long *count,
  32                                 unsigned int cpu);
  33 static struct timespec time_start, time_end;
  34
  35 static cstate_t mperf_cstates[MPERF_CSTATE_COUNT] = {
  36         {
  37                 .name                   = "C0",
  38                 .desc                   = N_("Processor Core not idle"),
  39                 .id                     = C0,
  40                 .range                  = RANGE_THREAD,
  41                 .get_count_percent      = mperf_get_count_percent,
  42         },
  43         {
  44                 .name                   = "Cx",
  45                 .desc                   = N_("Processor Core in an idle state"),
  46                 .id                     = Cx,
  47                 .range                  = RANGE_THREAD,
  48                 .get_count_percent      = mperf_get_count_percent,
  49         },
  50
  51         {
  52                 .name                   = "Freq",
  53                 .desc                   = N_("Average Frequency (including boost) in MHz"),
  54                 .id                     = AVG_FREQ,
  55                 .range                  = RANGE_THREAD,
  56                 .get_count              = mperf_get_count_freq,
  57         },
  58 };
  59
  60 enum MAX_FREQ_MODE { MAX_FREQ_SYSFS, MAX_FREQ_TSC_REF };
  61 static int max_freq_mode;
  62 /*
  63  * The max frequency mperf is ticking at (in C0), either retrieved via:
  64  *   1) calculated after measurements if we know TSC ticks at mperf/P0 frequency
  65  *   2) cpufreq /sys/devices/.../cpu0/cpufreq/cpuinfo_max_freq at init time
  66  * 1. Is preferred as it also works without cpufreq subsystem (e.g. on Xen)
  67  */
  68 static unsigned long max_frequency;
  69
  70 static unsigned long long tsc_at_measure_start;
  71 static unsigned long long tsc_at_measure_end;
  72 static unsigned long long *mperf_previous_count;
  73 static unsigned long long *aperf_previous_count;
  74 static unsigned long long *mperf_current_count;
  75 static unsigned long long *aperf_current_count;
  76
  77 /* valid flag for all CPUs. If a MSR read failed it will be zero */
  78 static int *is_valid;
  79
  80 static int mperf_get_tsc(unsigned long long *tsc)
  81 {
  82         int ret;
  83         ret = read_msr(0, MSR_TSC, tsc);
  84         if (ret)
  85                 dprint("Reading TSC MSR failed, returning %llu\n", *tsc);
  86         return ret;
  87 }
  88
  89 static int mperf_init_stats(unsigned int cpu)
  90 {
  91         unsigned long long val;
  92         int ret;
  93
  94         ret = read_msr(cpu, MSR_APERF, &val);
  95         aperf_previous_count[cpu] = val;
  96         ret |= read_msr(cpu, MSR_MPERF, &val);
  97         mperf_previous_count[cpu] = val;
  98         is_valid[cpu] = !ret;
  99
 100         return 0;
 101 }
 102
 103 static int mperf_measure_stats(unsigned int cpu)
 104 {
 105         unsigned long long val;
 106         int ret;
 107
 108         ret = read_msr(cpu, MSR_APERF, &val);
 109         aperf_current_count[cpu] = val;
 110         ret |= read_msr(cpu, MSR_MPERF, &val);
 111         mperf_current_count[cpu] = val;
 112         is_valid[cpu] = !ret;
 113
 114         return 0;
 115 }
 116
 117 static int mperf_get_count_percent(unsigned int id, double *percent,
 118                                    unsigned int cpu)
 119 {
 120         unsigned long long aperf_diff, mperf_diff, tsc_diff;
 121         unsigned long long timediff;
 122
 123         if (!is_valid[cpu])
 124                 return -1;
 125
 126         if (id != C0 && id != Cx)
 127                 return -1;
 128
 129         mperf_diff = mperf_current_count[cpu] - mperf_previous_count[cpu];
 130         aperf_diff = aperf_current_count[cpu] - aperf_previous_count[cpu];
 131
 132         if (max_freq_mode == MAX_FREQ_TSC_REF) {
 133                 tsc_diff = tsc_at_measure_end - tsc_at_measure_start;
 134                 *percent = 100.0 * mperf_diff / tsc_diff;
 135                 dprint("%s: TSC Ref - mperf_diff: %llu, tsc_diff: %llu\n",
 136                        mperf_cstates[id].name, mperf_diff, tsc_diff);
 137         } else if (max_freq_mode == MAX_FREQ_SYSFS) {
 138                 timediff = timespec_diff_us(time_start, time_end);
 139                 *percent = 100.0 * mperf_diff / timediff;
 140                 dprint("%s: MAXFREQ - mperf_diff: %llu, time_diff: %llu\n",
 141                        mperf_cstates[id].name, mperf_diff, timediff);
 142         } else
 143                 return -1;
 144
 145         if (id == Cx)
 146                 *percent = 100.0 - *percent;
 147
 148         dprint("%s: previous: %llu - current: %llu - (%u)\n",
 149                 mperf_cstates[id].name, mperf_diff, aperf_diff, cpu);
 150         dprint("%s: %f\n", mperf_cstates[id].name, *percent);
 151         return 0;
 152 }
 153
 154 static int mperf_get_count_freq(unsigned int id, unsigned long long *count,
 155                                 unsigned int cpu)
 156 {
 157         unsigned long long aperf_diff, mperf_diff, time_diff, tsc_diff;
 158
 159         if (id != AVG_FREQ)
 160                 return 1;
 161
 162         if (!is_valid[cpu])
 163                 return -1;
 164
 165         mperf_diff = mperf_current_count[cpu] - mperf_previous_count[cpu];
 166         aperf_diff = aperf_current_count[cpu] - aperf_previous_count[cpu];
 167
 168         if (max_freq_mode == MAX_FREQ_TSC_REF) {
 169                 /* Calculate max_freq from TSC count */
 170                 tsc_diff = tsc_at_measure_end - tsc_at_measure_start;
 171                 time_diff = timespec_diff_us(time_start, time_end);
 172                 max_frequency = tsc_diff / time_diff;
 173         }
 174
 175         *count = max_frequency * ((double)aperf_diff / mperf_diff);
 176         dprint("%s: Average freq based on %s maximum frequency:\n",
 177                mperf_cstates[id].name,
 178                (max_freq_mode == MAX_FREQ_TSC_REF) ? "TSC calculated" : "sysfs read");
 179         dprint("%max_frequency: %lu", max_frequency);
 180         dprint("aperf_diff: %llu\n", aperf_diff);
 181         dprint("mperf_diff: %llu\n", mperf_diff);
 182         dprint("avg freq:   %llu\n", *count);
 183         return 0;
 184 }
 185
 186 static int mperf_start(void)
 187 {
 188         int cpu;
 189         unsigned long long dbg;
 190
 191         clock_gettime(CLOCK_REALTIME, &time_start);
 192         mperf_get_tsc(&tsc_at_measure_start);
 193
 194         for (cpu = 0; cpu < cpu_count; cpu++)
 195                 mperf_init_stats(cpu);
 196
 197         mperf_get_tsc(&dbg);
 198         dprint("TSC diff: %llu\n", dbg - tsc_at_measure_start);
 199         return 0;
 200 }
 201
 202 static int mperf_stop(void)
 203 {
 204         unsigned long long dbg;
 205         int cpu;
 206
 207         for (cpu = 0; cpu < cpu_count; cpu++)
 208                 mperf_measure_stats(cpu);
 209
 210         mperf_get_tsc(&tsc_at_measure_end);
 211         clock_gettime(CLOCK_REALTIME, &time_end);
 212
 213         mperf_get_tsc(&dbg);
 214         dprint("TSC diff: %llu\n", dbg - tsc_at_measure_end);
 215
 216         return 0;
 217 }
 218
 219 /*
 220  * Mperf register is defined to tick at P0 (maximum) frequency
 221  *
 222  * Instead of reading out P0 which can be tricky to read out from HW,
 223  * we use TSC counter if it reliably ticks at P0/mperf frequency.
 224  *
 225  * Still try to fall back to:
 226  * /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq
 227  * on older Intel HW without invariant TSC feature.
 228  * Or on AMD machines where TSC does not tick at P0 (do not exist yet, but
 229  * it's still double checked (MSR_AMD_HWCR)).
 230  *
 231  * On these machines the user would still get useful mperf
 232  * stats when acpi-cpufreq driver is loaded.
 233  */
 234 static int init_maxfreq_mode(void)
 235 {
 236         int ret;
 237         unsigned long long hwcr;
 238         unsigned long min;
 239
 240         if (!cpupower_cpu_info.caps & CPUPOWER_CAP_INV_TSC)
 241                 goto use_sysfs;
 242
 243         if (cpupower_cpu_info.vendor == X86_VENDOR_AMD) {
 244                 /* MSR_AMD_HWCR tells us whether TSC runs at P0/mperf
 245                  * freq.
 246                  * A test whether hwcr is accessable/available would be:
 247                  * (cpupower_cpu_info.family > 0x10 ||
 248                  *   cpupower_cpu_info.family == 0x10 &&
 249                  *   cpupower_cpu_info.model >= 0x2))
 250                  * This should be the case for all aperf/mperf
 251                  * capable AMD machines and is therefore safe to test here.
 252                  * Compare with Linus kernel git commit: acf01734b1747b1ec4
 253                  */
 254                 ret = read_msr(0, MSR_AMD_HWCR, &hwcr);
 255                 /*
 256                  * If the MSR read failed, assume a Xen system that did
 257                  * not explicitly provide access to it and assume TSC works
 258                 */
 259                 if (ret != 0) {
 260                         dprint("TSC read 0x%x failed - assume TSC working\n",
 261                                MSR_AMD_HWCR);
 262                         return 0;
 263                 } else if (1 & (hwcr >> 24)) {
 264                         max_freq_mode = MAX_FREQ_TSC_REF;
 265                         return 0;
 266                 } else { /* Use sysfs max frequency if available */ }
 267         } else if (cpupower_cpu_info.vendor == X86_VENDOR_INTEL) {
 268                 /*
 269                  * On Intel we assume mperf (in C0) is ticking at same
 270                  * rate than TSC
 271                  */
 272                 max_freq_mode = MAX_FREQ_TSC_REF;
 273                 return 0;
 274         }
 275 use_sysfs:
 276         if (cpufreq_get_hardware_limits(0, &min, &max_frequency)) {
 277                 dprint("Cannot retrieve max freq from cpufreq kernel "
 278                        "subsystem\n");
 279                 return -1;
 280         }
 281         max_freq_mode = MAX_FREQ_SYSFS;
 282         return 0;
 283 }
 284
 285 /*
 286  * This monitor provides:
 287  *
 288  * 1) Average frequency a CPU resided in
 289  *    This always works if the CPU has aperf/mperf capabilities
 290  *
 291  * 2) C0 and Cx (any sleep state) time a CPU resided in
 292  *    Works if mperf timer stops ticking in sleep states which
 293  *    seem to be the case on all current HW.
 294  * Both is directly retrieved from HW registers and is independent
 295  * from kernel statistics.
 296  */
 297 struct cpuidle_monitor mperf_monitor;
 298 struct cpuidle_monitor *mperf_register(void)
 299 {
 300         if (!(cpupower_cpu_info.caps & CPUPOWER_CAP_APERF))
 301                 return NULL;
 302
 303         if (init_maxfreq_mode())
 304                 return NULL;
 305
 306         /* Free this at program termination */
 307         is_valid = calloc(cpu_count, sizeof(int));
 308         mperf_previous_count = calloc(cpu_count, sizeof(unsigned long long));
 309         aperf_previous_count = calloc(cpu_count, sizeof(unsigned long long));
 310         mperf_current_count = calloc(cpu_count, sizeof(unsigned long long));
 311         aperf_current_count = calloc(cpu_count, sizeof(unsigned long long));
 312
 313         mperf_monitor.name_len = strlen(mperf_monitor.name);
 314         return &mperf_monitor;
 315 }
 316
 317 void mperf_unregister(void)
 318 {
 319         free(mperf_previous_count);
 320         free(aperf_previous_count);
 321         free(mperf_current_count);
 322         free(aperf_current_count);
 323         free(is_valid);
 324 }
 325
 326 struct cpuidle_monitor mperf_monitor = {
 327         .name                   = "Mperf",
 328         .hw_states_num          = MPERF_CSTATE_COUNT,
 329         .hw_states              = mperf_cstates,
 330         .start                  = mperf_start,
 331         .stop                   = mperf_stop,
 332         .do_register            = mperf_register,
 333         .unregister             = mperf_unregister,
 334         .needs_root             = 1,
 335         .overflow_s             = 922000000 /* 922337203 seconds TSC overflow
 336                                                at 20GHz */
 337 };
 338 #endif /* #if defined(__i386__) || defined(__x86_64__) */