[mythtv-users] Is the GT220 the new chip of choice? (Idle power?)
Jarod Wilson
jarod at wilsonet.com
Fri Oct 23 13:35:40 UTC 2009
On Oct 23, 2009, at 3:30 AM, Andre Newman wrote:
> Having to turn off cpu speed changes to keep VDPAU fed at full
> bandwidth negates any other benefits for me right now, I need to
> find where in MythTV to change the CPU speed profile when playback
> starts and then revert it at the end.
MythTV doesn't do anything to change the cpu speed profile. The
*kernel* controls that on any modern system. (And on less modern ones,
its a userspace daemon called 'cpuspeed'). The cpu frequency scales
with demand, and the thresholds where scaling happens are entirely
tunable. Simply alter the idle/busy thresholds at which the cpu freq
governor (typically 'ondemand' these days) ramps up the clock speed.
The main place of interest is /sys/devices/system/cpu/cpu*/cpufreq/
ondemand/up_threshold.
For some distributions, there's an init script that sets up cpu freq
scaling on boot, and you can override the defaults by way of a config
file. Others may require rc.local dickery.
See also the kernel documentation that covers all this in <kernel
source>/Documentation/cpu-freq/
--
Jarod Wilson
jarod at wilsonet.com
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