On Mon, 27 Aug 2018, Kevin Cosgrove wrote:
# | sudo tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor
sudo touch /etc/rc.d/rc.local
cp /etc/rc.d/rc.local rc.local_cpufreq
cat << EOF >> rc.local_cpufreq
#!/bin/sh
Some things have changed with cpufreq.
- in days of old there was /etc/rc.d/*ondemand that ran 60 seconds after
startup. This means no matter what you set for cpufreq it gets
down graded 60 sec later. disable ondemand if your os comes with
it.
- Now days there is kernel modules that need to be loaded and effective
before changing cpufreq stuff, otherwise it doesn't work... and
ondemand has been moved to systemd to ensure this. So it is best
if your os uses systemd to move you cpufreq setting script to
systemd to replace ondemand. BTW this ondemand also waits 60
seconds.
- newer intel cpus have a thing called "Boost" that can change your cpus
frequency up and down above what performance sets it to. There are
three choices here: Turn boost off in bios. Turn it off at run
time. Set performances minimum and max speed to compensate...
maybe higher than performance would. (yes I have more xruns at
low latencies with Boost on)
Setting performance is not about making sure your cpu runs as fast as
possible. It is about making sure the cpu speed does not change, It seems
at speed down changes I get xruns. However, I have set cpu governor to
USER and set it hard to 800Mhz (lowest possible) and still very good xrun
performance (like none in 8 hours running) while ondemand still gives
xruns. So choose your speed and monitor cpu temperature and run it at the
speed that gives you the highest temperature you are comfortable with.
IMO you should be monitoring temperature anyway to catch dust build up or
fan failure.
--
Len Ovens
www.ovenwerks.net
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