gettime.c

   1 /*
   2  * Clock functions
   3  */
   4
   5 #include <unistd.h>
   6 #include <sys/time.h>
   7
   8 #include "fio.h"
   9
  10 #include "hash.h"
  11
  12 static int clock_gettime_works;
  13 static struct timeval last_tv;
  14 static int last_tv_valid;
  15
  16 #ifdef FIO_DEBUG_TIME
  17
  18 #define HASH_BITS       8
  19 #define HASH_SIZE       (1 << HASH_BITS)
  20
  21 static struct flist_head hash[HASH_SIZE];
  22 static int gtod_inited;
  23
  24 struct gtod_log {
  25         struct flist_head list;
  26         void *caller;
  27         unsigned long calls;
  28 };
  29
  30 static struct gtod_log *find_hash(void *caller)
  31 {
  32         unsigned long h = hash_ptr(caller, HASH_BITS);
  33         struct flist_head *entry;
  34
  35         flist_for_each(entry, &hash[h]) {
  36                 struct gtod_log *log = flist_entry(entry, struct gtod_log,
  37                                                                         list);
  38
  39                 if (log->caller == caller)
  40                         return log;
  41         }
  42
  43         return NULL;
  44 }
  45
  46 static struct gtod_log *find_log(void *caller)
  47 {
  48         struct gtod_log *log = find_hash(caller);
  49
  50         if (!log) {
  51                 unsigned long h;
  52
  53                 log = malloc(sizeof(*log));
  54                 INIT_FLIST_HEAD(&log->list);
  55                 log->caller = caller;
  56                 log->calls = 0;
  57
  58                 h = hash_ptr(caller, HASH_BITS);
  59                 flist_add_tail(&log->list, &hash[h]);
  60         }
  61
  62         return log;
  63 }
  64
  65 static void gtod_log_caller(void *caller)
  66 {
  67         if (gtod_inited) {
  68                 struct gtod_log *log = find_log(caller);
  69
  70                 log->calls++;
  71         }
  72 }
  73
  74 static void fio_exit fio_dump_gtod(void)
  75 {
  76         unsigned long total_calls = 0;
  77         int i;
  78
  79         for (i = 0; i < HASH_SIZE; i++) {
  80                 struct flist_head *entry;
  81                 struct gtod_log *log;
  82
  83                 flist_for_each(entry, &hash[i]) {
  84                         log = flist_entry(entry, struct gtod_log, list);
  85
  86                         printf("function %p, calls %lu\n", log->caller,
  87                                                                 log->calls);
  88                         total_calls += log->calls;
  89                 }
  90         }
  91
  92         printf("Total %lu gettimeofday\n", total_calls);
  93 }
  94
  95 static void fio_init gtod_init(void)
  96 {
  97         int i;
  98
  99         for (i = 0; i < HASH_SIZE; i++)
 100                 INIT_FLIST_HEAD(&hash[i]);
 101
 102         gtod_inited = 1;
 103 }
 104
 105 #endif /* FIO_DEBUG_TIME */
 106
 107 #ifdef FIO_DEBUG_TIME
 108 void fio_gettime(struct timeval *tp, void *caller)
 109 #else
 110 void fio_gettime(struct timeval *tp, void fio_unused *caller)
 111 #endif
 112 {
 113 #ifdef FIO_DEBUG_TIME
 114         if (!caller)
 115                 caller = __builtin_return_address(0);
 116
 117         gtod_log_caller(caller);
 118 #endif
 119         if (!clock_gettime_works) {
 120 gtod:
 121                 gettimeofday(tp, NULL);
 122         } else {
 123                 struct timespec ts;
 124
 125                 if (clock_gettime(CLOCK_MONOTONIC, &ts) < 0) {
 126                         clock_gettime_works = 0;
 127                         goto gtod;
 128                 }
 129
 130                 tp->tv_sec = ts.tv_sec;
 131                 tp->tv_usec = ts.tv_nsec / 1000;
 132         }
 133
 134         /*
 135          * If Linux is using the tsc clock on non-synced processors,
 136          * sometimes time can appear to drift backwards. Fix that up.
 137          */
 138         if (last_tv_valid) {
 139                 if (tp->tv_sec < last_tv.tv_sec)
 140                         tp->tv_sec = last_tv.tv_sec;
 141                 else if (last_tv.tv_sec == tp->tv_sec &&
 142                          tp->tv_usec < last_tv.tv_usec)
 143                         tp->tv_usec = last_tv.tv_usec;
 144         }
 145         last_tv_valid = 1;
 146         memcpy(&last_tv, tp, sizeof(*tp));
 147 }