[Techteam] XO-1.5 Kernel Update (i.e My Weekly Status)

Benjamin M. Schwartz bmschwar at fas.harvard.edu
Mon Jul 20 17:19:12 EDT 2009

Benjamin M. Schwartz wrote:
> Audio playback and recording don't use userspace timers, but they do
> generate a lot of interrupts.  If cpuidle does something even marginally
> sane with interrupt history, it should not go into a high-latency sleep
> state during sound playback or recording.  If it does, audio will skip,
> but the CPU will be woken up by every interrupt delivered from the sound
> card.  (It occurs to me that this probably should've happened for the XO-1
> too, but it didn't.  Maybe the EC is not handling those interrupts properly?)

On second thought, the Geode's audio codec was probably powered off along
with the CPU.  I imagine there's a way to use the kernel's Power
Management QoS to prevent this from happening, but I don't know the details.


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