From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Fri, 23 Feb 2018 11:30:20 +0000 (+0100)
Subject: sourcestats: limit minimum value of std_dev
X-Git-Tag: 3.3-pre1~34
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e79a6c21164c84d35b699349839a88a7ee13745b;p=thirdparty%2Fchrony.git

sourcestats: limit minimum value of std_dev
---

diff --git a/sourcestats.c b/sourcestats.c
index 9c1c4dec..ff4c652e 100644
--- a/sourcestats.c
+++ b/sourcestats.c
@@ -51,6 +51,9 @@
 #define MIN_SKEW 1.0e-12
 #define MAX_SKEW 1.0e+02
 
+/* The minimum standard deviation */
+#define MIN_STDDEV 1.0e-9
+
 /* The asymmetry of network jitter when all jitter is in one direction */
 #define MAX_ASYMMETRY 0.5
 
@@ -571,7 +574,7 @@ SST_DoNewRegression(SST_Stats inst)
     inst->estimated_offset = est_intercept;
     inst->offset_time = inst->sample_times[inst->last_sample];
     inst->estimated_offset_sd = est_intercept_sd;
-    inst->std_dev = sqrt(est_var);
+    inst->std_dev = MAX(MIN_STDDEV, sqrt(est_var));
     inst->nruns = nruns;
 
     inst->skew = CLAMP(MIN_SKEW, inst->skew, MAX_SKEW);