From: Jens Axboe <jens.axboe@oracle.com>
Date: Wed, 3 Jan 2007 10:10:27 +0000 (+0100)
Subject: [PATCH] Fix division by zero in deviance calculation
X-Git-Tag: fio-1.11~10
X-Git-Url: https://git.kernel.dk/?p=fio.git;a=commitdiff_plain;h=e6d276f2c07cc35f3d57210713e8288bb44daf97;ds=sidebyside

[PATCH] Fix division by zero in deviance calculation

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---

diff --git a/stat.c b/stat.c
index b4facc7e..6e55925b 100644
--- a/stat.c
+++ b/stat.c
@@ -281,8 +281,12 @@ static int calc_lat(struct io_stat *is, unsigned long *min, unsigned long *max,
 
 	n = (double) is->samples;
 	*mean = (double) is->val / n;
-	*dev = sqrt(((double) is->val_sq - (*mean * *mean) / n) / (n - 1));
+	*dev = 0;
+
+	if (n <= 1)
+		return 1;
 
+	*dev = sqrt(((double) is->val_sq - (*mean * *mean) / n) / (n - 1));
 	return 1;
 }