busybox: ntpd: increase SLEW_THRESHOLD from 0.125 to 0.5 (backport)

Original commit: 8502fa8747e962f69084be09ff8b930e0fb0c449
RMerl · May 13, 2019 · 2a95dd4 · 2a95dd4
1 parent 0faeab4
commit 2a95dd4
Showing 1 changed file with 4 additions and 6 deletions.
diff --git a/release/src/router/busybox/networking/ntpd.c b/release/src/router/busybox/networking/ntpd.c
@@ -138,13 +138,11 @@
  */
 #define STEP_THRESHOLD     1
 /* Slew threshold (sec): adjtimex() won't accept offsets larger than this.
- * Using exact power of 2 (1/8) results in smaller code
+ * Using exact power of 2 (1/8, 1/2 etc) results in smaller code
  */
-#define SLEW_THRESHOLD 0.25
+#define SLEW_THRESHOLD   0.5
-/* Stepout threshold (sec). std ntpd uses 900 (11 mins (!)) */
+// ^^^^ used to be 0.125.
-//^^^^^^^^^^^^^^^^^^^^^^^^^^ TODO: man adjtimex about tmx.offset:
+// Since Linux 2.6.26 (circa 2006), kernel accepts (-0.5s, +0.5s) range
-// "Since Linux 2.6.26, the supplied value is clamped to the range (-0.5s, +0.5s)"
-// - can use this larger value instead?
 
 /* Stepout threshold (sec). std ntpd uses 900 (11 mins (!)) */
 //UNUSED: #define WATCH_THRESHOLD  128