On 08/05/2012 10:04 PM, Ralf Mardorf wrote:
On Sun, 2012-08-05 at 21:39 +0200, Jeremy Jongepier
wrote:
"The command in your /etc/rc.local file only works if you
disable the ondemand service. On Debian systems:
sudo update-rc.d ondemand disable
Another option would be to modify the ondemand init script and
rename it to performance:
sudo sed -i 's/ondemand/performance/g' /etc/init.d/ondemand
sudo update-rc.d ondemand disable
sudo cp /etc/init.d/ondemand /etc/init.d/performance
sudo update-rc.d performance enable"
Last time I used Debian there was a script /etc/init.d/cpufrequtils that
set up the governor to ondemand. It's not that long ago, so I guess for
Debian this didn't change. Len of course refers to Ubuntu (Studio).
AV Linux (Debian) also has got /etc/init.d/cpufrequtils:
"[snip]
# Set ENABLE to "true" to let the script run at boot time.
#
# eg: ENABLE="true"
# GOVERNOR="ondemand"
# MAX_SPEED=1000
# MIN_SPEED=500
ENABLE="true"
GOVERNOR="performance"
MAX_SPEED="0"
MIN_SPEED="0"
[snip]"
I once wrote a script to toggle between ondemand and performance, not
only for the session, but also to keep it for next startup, based
on /etc/init.d/cpufrequtils.
Regards,
Ralf
I really wonder why you are all raving about this.
Well, it is hard to generalize but on most modern CPUs + main-boards CPU
frequency scaling is _not_ correlated to audio-dropouts [anymore] and a
non-issue.
The time it takes to change CPU frequencies is very small compared (us)
to [even] low-latency audio (ms). Concerning Hardware, these days,
bus-power-management is most often the cause of xruns on idle systems
followed by SMI.
Disable PCI and/or PCIe power-management in the BIOS and also disable
EIST and C1E halt-states; and, the 'ondemand' governor will works just fine.
If you have an unlimited supply of power and noise of cooling
the system is of no concern: sure, use the 'performance' CPU-freq
governor -- reducing the number of possibilities in complex systems
usually increases reliability... which is indeed a good thing for audio.
ciao,
robin
NB. frequency scaling _can_ be an issue when using jack2 (or tschak) on
a multi-core machine: The total system-load (over all CPUs) may still be
too low for the CPU governor to react, while DSP load is already at the
limit. --
http://rg42.org/oss/jackfreqd/