There is an issue in FIO when using the detailed bandwidth and iops logging with averaging over a period of time > 1 second.
It seems that usecs overflows which later causes negative time diff values resulting in skewed toward 0 results.
I have attached a potential fix that should prevent usecs from going beyond 1000000.
diff --git a/time.c b/time.c
index f5dc049..c748bee 100644
--- a/time.c
+++ b/time.c
@@ -8,11 +8,18 @@ static unsigned long ns_granularity;
void timeval_add_msec(struct timeval *tv, unsigned int msec)
{
- tv->tv_usec += 1000 * msec;
- if (tv->tv_usec >= 1000000) {
- tv->tv_usec -= 1000000;
- tv->tv_sec++;
- }
+ int adj_usec = 1000 * msec;
+ int adj_sec = 0;
+ tv->tv_usec += adj_usec;
+ if (adj_usec >= 1000000) {
+ adj_sec = adj_usec / 1000000;
+ tv->tv_usec -= adj_sec * 1000000;
+ tv->tv_sec += adj_sec;
+ }
+ if (tv->tv_usec >= 1000000){
+ tv->tv_usec -= 1000000;
+ tv->tv_sec++;
+ }
}
/*
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