[Freeswitch-users] Linux clocksource TSC vs HPET

François fdelawarde at wirelessmundi.com
Fri Jan 22 15:22:47 MSK 2016

Hi all,

I'm trying to find a solution for an "RT throttling" issue under 
relatively high load (20cps) on linux 3.10 and CPU Xeon E5-1650v2 
(6cores). A similar jira ticket FS-8620 has a recommendation to set the 
clocksource to "hpet":

echo hpet > /sys/devices/system/clocksource/clocksource0/current_clocksource

I read somewhere that the default clocksource (TSC) is lighter in CPU 
usage because it only requires reading a register that is synchronized 
across all cores...

Considering FreeSWITCH needs:

-> Is HPET recommended over the default "TSC" clock?

-> Does a change in clocksource have immediate effects or does it 
require an FS restart/reboot?

-> Also, is it recommended to disable RT-throttling to resolve these 
types of issues?

echo -1 >/proc/sys/kernel/sched_rt_runtime_us
echo -1 >/proc/sys/kernel/sched_rt_period_us


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