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 static struct timeval *fio_tv;
  23 int fio_gtod_offload = 0;
  24 int fio_gtod_cpu = -1;
  25
  26 enum fio_cs fio_clock_source = CS_GTOD;
  27
  28 #ifdef FIO_DEBUG_TIME
  29
  30 #define HASH_BITS       8
  31 #define HASH_SIZE       (1 << HASH_BITS)
  32
  33 static struct flist_head hash[HASH_SIZE];
  34 static int gtod_inited;
  35
  36 struct gtod_log {
  37         struct flist_head list;
  38         void *caller;
  39         unsigned long calls;
  40 };
  41
  42 static struct gtod_log *find_hash(void *caller)
  43 {
  44         unsigned long h = hash_ptr(caller, HASH_BITS);
  45         struct flist_head *entry;
  46
  47         flist_for_each(entry, &hash[h]) {
  48                 struct gtod_log *log = flist_entry(entry, struct gtod_log,
  49                                                                         list);
  50
  51                 if (log->caller == caller)
  52                         return log;
  53         }
  54
  55         return NULL;
  56 }
  57
  58 static struct gtod_log *find_log(void *caller)
  59 {
  60         struct gtod_log *log = find_hash(caller);
  61
  62         if (!log) {
  63                 unsigned long h;
  64
  65                 log = malloc(sizeof(*log));
  66                 INIT_FLIST_HEAD(&log->list);
  67                 log->caller = caller;
  68                 log->calls = 0;
  69
  70                 h = hash_ptr(caller, HASH_BITS);
  71                 flist_add_tail(&log->list, &hash[h]);
  72         }
  73
  74         return log;
  75 }
  76
  77 static void gtod_log_caller(void *caller)
  78 {
  79         if (gtod_inited) {
  80                 struct gtod_log *log = find_log(caller);
  81
  82                 log->calls++;
  83         }
  84 }
  85
  86 static void fio_exit fio_dump_gtod(void)
  87 {
  88         unsigned long total_calls = 0;
  89         int i;
  90
  91         for (i = 0; i < HASH_SIZE; i++) {
  92                 struct flist_head *entry;
  93                 struct gtod_log *log;
  94
  95                 flist_for_each(entry, &hash[i]) {
  96                         log = flist_entry(entry, struct gtod_log, list);
  97
  98                         printf("function %p, calls %lu\n", log->caller,
  99                                                                 log->calls);
 100                         total_calls += log->calls;
 101                 }
 102         }
 103
 104         printf("Total %lu gettimeofday\n", total_calls);
 105 }
 106
 107 static void fio_init gtod_init(void)
 108 {
 109         int i;
 110
 111         for (i = 0; i < HASH_SIZE; i++)
 112                 INIT_FLIST_HEAD(&hash[i]);
 113
 114         gtod_inited = 1;
 115 }
 116
 117 #endif /* FIO_DEBUG_TIME */
 118
 119 #ifdef FIO_DEBUG_TIME
 120 void fio_gettime(struct timeval *tp, void *caller)
 121 #else
 122 void fio_gettime(struct timeval *tp, void fio_unused *caller)
 123 #endif
 124 {
 125 #ifdef FIO_DEBUG_TIME
 126         if (!caller)
 127                 caller = __builtin_return_address(0);
 128
 129         gtod_log_caller(caller);
 130 #endif
 131         if (fio_tv) {
 132                 memcpy(tp, fio_tv, sizeof(*tp));
 133                 return;
 134         }
 135
 136         switch (fio_clock_source) {
 137         case CS_GTOD:
 138                 gettimeofday(tp, NULL);
 139                 break;
 140         case CS_CGETTIME: {
 141                 struct timespec ts;
 142
 143                 if (clock_gettime(CLOCK_REALTIME, &ts) < 0) {
 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 void fio_gtod_init(void)
 266 {
 267         fio_tv = smalloc(sizeof(struct timeval));
 268         assert(fio_tv);
 269 }
 270
 271 void fio_gtod_update(void)
 272 {
 273         gettimeofday(fio_tv, NULL);
 274 }