In commit 23eecad7b48913b12bd83917647de99e66d69b49 (2021-10-13) I
lowered the timer frequency from 1 000 Hz to 100 Hz, but while I wasn't
able to recognize a reproducible drop in energy consumption there were
some heavy-load situations when the system started to stutter.
Setting it to 300 Hz as some binary distributions do sounds therfor like
a sane decision.
Trying out a lower time frequency and check if it has any influence at all
after a short discussion in IRC about it.
To me it looks as there is no real impact on my hardware with this
After a debate in IRC and some reading it looks to me as there is no general
rule but many people with opinions. Therefore I don’t expect a difference in
overall power consumption or responsiveness, but will just try it out.
I set up a quick and dirty battery test:
- display brightness at 35 %
- wifi on
- bluetooth off
- some default background deamons running (cron, chrony/NTP, syncthing)
- one termina (konsole) open
- that energy monitor from KDE open
- CPU boost disabled with 'echo 0 > /sys/devices/system/cpu/cpufreq/boost'
- verified that temperatures are low enough that the fan is off
Both setups (5.14.11-T14s with CONFIG_HZ_1000=y vs. 5.14.12-T14s
with CONFIG_HZ_100=y) showed values around 5.6 W, down to 5.2 W, up to > 30W
as I called emerge to check if it's not just a display glitch.
As this is a Notebook I don't have to care at all about some video cards and
TV frequencies that are mentioned in various threads.
To end this commit message I’d like to share a quote that amused me during my
mini-research:
„864Hz is indeed the win - I won't use a kernel wihout that option anymore.”
- User “creidiki”, forums.gentoo.org
Knobs to read -- and write -- should be visible in
/sys/class/firmware-attributes/*
For more details see Documentation/ABI/testing/sysfs-class-firmware-attributes.
This reverts the remaining options from earlier commit
4a4699674f58e72604f8eb1f74f23f253d19b801 because actually I do not trust
the TPM for my personal thread model enough and it doesn't support the
GPG ciphers I want to use. (Instead I use an external USB token again.)
