ntp: Make periodic RTC update more reliable
authorMiroslav Lichvar <mlichvar@redhat.com>
Thu, 1 Aug 2013 17:31:35 +0000 (19:31 +0200)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Sun, 8 Dec 2013 15:29:28 +0000 (07:29 -0800)
commit9baca2ff1035fbdc7f910a4b6fb34d4bec3f443b
treeac75d1ab045271da6b89cc243b4d1ee543cb65d1
parent72b9401c2f5ac465d97969ef7933753642bde8bf
ntp: Make periodic RTC update more reliable

commit a97ad0c4b447a132a322cedc3a5f7fa4cab4b304 upstream.

The current code requires that the scheduled update of the RTC happens
in the closest tick to the half of the second. This seems to be
difficult to achieve reliably. The scheduled work may be missing the
target time by a tick or two and be constantly rescheduled every second.

Relax the limit to 10 ticks. As a typical RTC drifts in the 11-minute
update interval by several milliseconds, this shouldn't affect the
overall accuracy of the RTC much.

Signed-off-by: Miroslav Lichvar <mlichvar@redhat.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Josh Boyer <jwboyer@fedoraproject.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
kernel/time/ntp.c