gettime.c

   1 /*
   2  * Clock functions
   3  */
   4
   5 #include <unistd.h>
   6 #include <math.h>
   7 #include <sys/time.h>
   8 #include <time.h>
   9
  10 #include "fio.h"
  11 #include "smalloc.h"
  12
  13 #include "hash.h"
  14
  15 #ifdef ARCH_HAVE_CPU_CLOCK
  16 static unsigned long cycles_per_usec;
  17 static unsigned long last_cycles;
  18 #endif
  19 static struct timeval last_tv;
  20 static int last_tv_valid;
  21
  22 enum fio_cs fio_clock_source = FIO_PREFERRED_CLOCK_SOURCE;
  23
  24 #ifdef FIO_DEBUG_TIME
  25
  26 #define HASH_BITS       8
  27 #define HASH_SIZE       (1 << HASH_BITS)
  28
  29 static struct flist_head hash[HASH_SIZE];
  30 static int gtod_inited;
  31
  32 struct gtod_log {
  33         struct flist_head list;
  34         void *caller;
  35         unsigned long calls;
  36 };
  37
  38 static struct gtod_log *find_hash(void *caller)
  39 {
  40         unsigned long h = hash_ptr(caller, HASH_BITS);
  41         struct flist_head *entry;
  42
  43         flist_for_each(entry, &hash[h]) {
  44                 struct gtod_log *log = flist_entry(entry, struct gtod_log,
  45                                                                         list);
  46
  47                 if (log->caller == caller)
  48                         return log;
  49         }
  50
  51         return NULL;
  52 }
  53
  54 static struct gtod_log *find_log(void *caller)
  55 {
  56         struct gtod_log *log = find_hash(caller);
  57
  58         if (!log) {
  59                 unsigned long h;
  60
  61                 log = malloc(sizeof(*log));
  62                 INIT_FLIST_HEAD(&log->list);
  63                 log->caller = caller;
  64                 log->calls = 0;
  65
  66                 h = hash_ptr(caller, HASH_BITS);
  67                 flist_add_tail(&log->list, &hash[h]);
  68         }
  69
  70         return log;
  71 }
  72
  73 static void gtod_log_caller(void *caller)
  74 {
  75         if (gtod_inited) {
  76                 struct gtod_log *log = find_log(caller);
  77
  78                 log->calls++;
  79         }
  80 }
  81
  82 static void fio_exit fio_dump_gtod(void)
  83 {
  84         unsigned long total_calls = 0;
  85         int i;
  86
  87         for (i = 0; i < HASH_SIZE; i++) {
  88                 struct flist_head *entry;
  89                 struct gtod_log *log;
  90
  91                 flist_for_each(entry, &hash[i]) {
  92                         log = flist_entry(entry, struct gtod_log, list);
  93
  94                         printf("function %p, calls %lu\n", log->caller,
  95                                                                 log->calls);
  96                         total_calls += log->calls;
  97                 }
  98         }
  99
 100         printf("Total %lu gettimeofday\n", total_calls);
 101 }
 102
 103 static void fio_init gtod_init(void)
 104 {
 105         int i;
 106
 107         for (i = 0; i < HASH_SIZE; i++)
 108                 INIT_FLIST_HEAD(&hash[i]);
 109
 110         gtod_inited = 1;
 111 }
 112
 113 #endif /* FIO_DEBUG_TIME */
 114
 115 #ifdef FIO_DEBUG_TIME
 116 void fio_gettime(struct timeval *tp, void *caller)
 117 #else
 118 void fio_gettime(struct timeval *tp, void fio_unused *caller)
 119 #endif
 120 {
 121 #ifdef FIO_DEBUG_TIME
 122         if (!caller)
 123                 caller = __builtin_return_address(0);
 124
 125         gtod_log_caller(caller);
 126 #endif
 127         if (fio_tv) {
 128                 memcpy(tp, fio_tv, sizeof(*tp));
 129                 return;
 130         }
 131
 132         switch (fio_clock_source) {
 133         case CS_GTOD:
 134                 gettimeofday(tp, NULL);
 135                 break;
 136         case CS_CGETTIME: {
 137                 struct timespec ts;
 138
 139 #ifdef FIO_HAVE_CLOCK_MONOTONIC
 140                 if (clock_gettime(CLOCK_MONOTONIC, &ts) < 0) {
 141 #else
 142                 if (clock_gettime(CLOCK_REALTIME, &ts) < 0) {
 143 #endif
 144                         log_err("fio: clock_gettime fails\n");
 145                         assert(0);
 146                 }
 147
 148                 tp->tv_sec = ts.tv_sec;
 149                 tp->tv_usec = ts.tv_nsec / 1000;
 150                 break;
 151                 }
 152 #ifdef ARCH_HAVE_CPU_CLOCK
 153         case CS_CPUCLOCK: {
 154                 unsigned long long usecs, t;
 155
 156                 t = get_cpu_clock();
 157                 if (t < last_cycles) {
 158                         dprint(FD_TIME, "CPU clock going back in time\n");
 159                         t = last_cycles;
 160                 }
 161
 162                 usecs = t / cycles_per_usec;
 163                 tp->tv_sec = usecs / 1000000;
 164                 tp->tv_usec = usecs % 1000000;
 165                 last_cycles = t;
 166                 break;
 167                 }
 168 #endif
 169         default:
 170                 log_err("fio: invalid clock source %d\n", fio_clock_source);
 171                 break;
 172         }
 173
 174         /*
 175          * If Linux is using the tsc clock on non-synced processors,
 176          * sometimes time can appear to drift backwards. Fix that up.
 177          */
 178         if (last_tv_valid) {
 179                 if (tp->tv_sec < last_tv.tv_sec)
 180                         tp->tv_sec = last_tv.tv_sec;
 181                 else if (last_tv.tv_sec == tp->tv_sec &&
 182                          tp->tv_usec < last_tv.tv_usec)
 183                         tp->tv_usec = last_tv.tv_usec;
 184         }
 185         last_tv_valid = 1;
 186         memcpy(&last_tv, tp, sizeof(*tp));
 187 }
 188
 189 #ifdef ARCH_HAVE_CPU_CLOCK
 190 static unsigned long get_cycles_per_usec(void)
 191 {
 192         struct timeval s, e;
 193         unsigned long long c_s, c_e;
 194
 195         gettimeofday(&s, NULL);
 196         c_s = get_cpu_clock();
 197         do {
 198                 unsigned long long elapsed;
 199
 200                 gettimeofday(&e, NULL);
 201                 elapsed = utime_since(&s, &e);
 202                 if (elapsed >= 10) {
 203                         c_e = get_cpu_clock();
 204                         break;
 205                 }
 206         } while (1);
 207
 208         return c_e - c_s;
 209 }
 210
 211 static void calibrate_cpu_clock(void)
 212 {
 213         double delta, mean, S;
 214         unsigned long avg, cycles[10];
 215         int i, samples;
 216
 217         cycles[0] = get_cycles_per_usec();
 218         S = delta = mean = 0.0;
 219         for (i = 0; i < 10; i++) {
 220                 cycles[i] = get_cycles_per_usec();
 221                 delta = cycles[i] - mean;
 222                 if (delta) {
 223                         mean += delta / (i + 1.0);
 224                         S += delta * (cycles[i] - mean);
 225                 }
 226         }
 227
 228         S = sqrt(S / (10 - 1.0));
 229
 230         samples = avg = 0;
 231         for (i = 0; i < 10; i++) {
 232                 double this = cycles[i];
 233
 234                 if ((fmax(this, mean) - fmin(this, mean)) > S)
 235                         continue;
 236                 samples++;
 237                 avg += this;
 238         }
 239
 240         S /= 10.0;
 241         mean /= 10.0;
 242
 243         for (i = 0; i < 10; i++)
 244                 dprint(FD_TIME, "cycles[%d]=%lu\n", i, cycles[i] / 10);
 245
 246         avg /= (samples * 10);
 247         dprint(FD_TIME, "avg: %lu\n", avg);
 248         dprint(FD_TIME, "mean=%f, S=%f\n", mean, S);
 249
 250         cycles_per_usec = avg;
 251
 252 }
 253 #else
 254 static void calibrate_cpu_clock(void)
 255 {
 256 }
 257 #endif
 258
 259 void fio_clock_init(void)
 260 {
 261         last_tv_valid = 0;
 262         calibrate_cpu_clock();
 263 }
 264
 265 unsigned long long utime_since(struct timeval *s, struct timeval *e)
 266 {
 267         long sec, usec;
 268         unsigned long long ret;
 269
 270         sec = e->tv_sec - s->tv_sec;
 271         usec = e->tv_usec - s->tv_usec;
 272         if (sec > 0 && usec < 0) {
 273                 sec--;
 274                 usec += 1000000;
 275         }
 276
 277         /*
 278          * time warp bug on some kernels?
 279          */
 280         if (sec < 0 || (sec == 0 && usec < 0))
 281                 return 0;
 282
 283         ret = sec * 1000000ULL + usec;
 284
 285         return ret;
 286 }
 287
 288 unsigned long long utime_since_now(struct timeval *s)
 289 {
 290         struct timeval t;
 291
 292         fio_gettime(&t, NULL);
 293         return utime_since(s, &t);
 294 }
 295
 296 unsigned long mtime_since(struct timeval *s, struct timeval *e)
 297 {
 298         long sec, usec, ret;
 299
 300         sec = e->tv_sec - s->tv_sec;
 301         usec = e->tv_usec - s->tv_usec;
 302         if (sec > 0 && usec < 0) {
 303                 sec--;
 304                 usec += 1000000;
 305         }
 306
 307         if (sec < 0 || (sec == 0 && usec < 0))
 308                 return 0;
 309
 310         sec *= 1000UL;
 311         usec /= 1000UL;
 312         ret = sec + usec;
 313
 314         return ret;
 315 }
 316
 317 unsigned long mtime_since_now(struct timeval *s)
 318 {
 319         struct timeval t;
 320         void *p = __builtin_return_address(0);
 321
 322         fio_gettime(&t, p);
 323         return mtime_since(s, &t);
 324 }
 325
 326 unsigned long time_since_now(struct timeval *s)
 327 {
 328         return mtime_since_now(s) / 1000;
 329 }