From 7c22c78550440f4111712fce01c022fcdc2441d4 Mon Sep 17 00:00:00 2001 From: "Gary E. Miller" Date: Thu, 30 Jun 2016 20:36:49 -0700 Subject: Add a mention to use only the performance governor. Having the CPU change frequencies and idle states adds errors to the timekeeping. --- www/gpsd-time-service-howto.txt | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'www') diff --git a/www/gpsd-time-service-howto.txt b/www/gpsd-time-service-howto.txt index 3b5452c2..5cf84ca1 100644 --- a/www/gpsd-time-service-howto.txt +++ b/www/gpsd-time-service-howto.txt @@ -1104,7 +1104,7 @@ improved local and remote offsets. Normally enabling power saving features is a good thing: it saves you power. But when your CPU changes power saving modes (cstates for Intel CPUs) the impact on PPS timing is noticeable. For some reason the NO_HZ kernel -mode has a similar bad effecct on timekeeping. +mode has a similar bad effect on timekeeping. To improve your timekeeping, turn off both features on Intel CPUs by adding this to your boot command line: @@ -1119,6 +1119,10 @@ For ARM, be sure NO_HZ is off: nohz=off ----------------------------------------------------------------------------- +You will also need to select the 'performance' CPU governor to keep ypur +CPU set to the maximum speed for continuous usage. How you see and set +your governor will be distribution specific. The easiest way it to +recompile your kernel to only provide the performance governor. == NTP tuning and performance details == -- cgit v1.2.1