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inline | side by side (from parent 1:
e6d276f)
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
- unsigned long val;
- unsigned long val_sq;
+ unsigned long long val;
+ unsigned long long val_sq;
unsigned long max_val;
unsigned long min_val;
unsigned long samples;
unsigned long max_val;
unsigned long min_val;
unsigned long samples;
static int calc_lat(struct io_stat *is, unsigned long *min, unsigned long *max,
double *mean, double *dev)
{
static int calc_lat(struct io_stat *is, unsigned long *min, unsigned long *max,
double *mean, double *dev)
{
if (is->samples == 0)
return 0;
if (is->samples == 0)
return 0;
n = (double) is->samples;
*mean = (double) is->val / n;
n = (double) is->samples;
*mean = (double) is->val / n;
- *dev = sqrt(((double) is->val_sq - (*mean * *mean) / n) / (n - 1));
+ o = (double) is->val_sq - ((*mean * *mean) / n);
+ if (o < 0.0)
+ *dev = -1.0;
+ else
+ *dev = sqrt(o / (n - 1.0));
+