Attempt to work-around possible time warp

[fio.git] / time.c

diff --git a/time.c b/time.c
index 108c0fcaab09e4b0a7d0bcfba8c6e690e83541de..4fbc98bbc57f8b781d95c7a8362ce8b8ab348700 100644 (file)
--- a/time.c
+++ b/time.c
@@ -8,7 +8,7 @@ static unsigned long ns_granularity;
 
 unsigned long utime_since(struct timeval *s, struct timeval *e)
 {
-       long sec, usec;
+       long sec, usec, ret;
 
        sec = e->tv_sec - s->tv_sec;
        usec = e->tv_usec - s->tv_usec;
@@ -17,9 +17,16 @@ unsigned long utime_since(struct timeval *s, struct timeval *e)
                usec += 1000000;
        }
 
-       sec *= (double) 1000000;
+       sec *= 1000000UL;
+       ret = sec + usec;
 
-       return sec + usec;
+       /*
+        * time warp bug on some kernels?
+        */
+       if (ret < 0)
+               ret = 0;
+
+       return ret;
 }
 
 unsigned long utime_since_now(struct timeval *s)
@@ -32,7 +39,7 @@ unsigned long utime_since_now(struct timeval *s)
 
 unsigned long mtime_since(struct timeval *s, struct timeval *e)
 {
-       long sec, usec;
+       long sec, usec, ret;
 
        sec = e->tv_sec - s->tv_sec;
        usec = e->tv_usec - s->tv_usec;
@@ -41,10 +48,17 @@ unsigned long mtime_since(struct timeval *s, struct timeval *e)
                usec += 1000000;
        }
 
-       sec *= (double) 1000;
-       usec /= (double) 1000;
+       sec *= 1000UL;
+       usec /= 1000UL;
+       ret = sec + usec;
+
+       /*
+        * time warp bug on some kernels?
+        */
+       if (ret < 0)
+               ret = 0;
 
-       return sec + usec;
+       return ret;
 }
 
 unsigned long mtime_since_now(struct timeval *s)