[alsa-devel] pulseaudio eats 19% CPU power in Fedora 12

[Colin Guthrie]

'Twas brillig, and Raymond Yau at 21/04/10 01:30 did gyre and gimble:
> 2010/4/19 Daniel Chen <seven.steps at gmail.com>
> 
>>  but, like
>> Lennart suggests, these are by no means *caused* by PulseAudio.
>>
>> Best,
>> -Dan
>>
>>
> There are other factor affecting CPU usage  significantly
> 
> 1) the number of pulseaudio clients connected to PA server (i.e. number of
> audio stream need to be mixed )
> 2) the accuracy of system timer and the clock of the sound chip
> 3) the latency requirement of the different PA clients
> 4) the resampling method
> 5) the cpu loading of the system
> 6) the period time/period size selected by PA server to configure the alsa
> driver
> 
> why do you ruled out the cause ?
> 
>>> If you use "pacat" you can play audio with almost zero CPU
> usage
> 
> do you get the zero CPU usage in  Ubuntu 9.04/Ubuntu 9.10 with pacat on your
> machines ?

The pacat support for proper latency adjustment is only available in
more recent PA versions (with some , so chances are the older distros
wont have them (although I believe a 9.10 version of 0.9.21+stable-queue
exists somewhere.


These commits from stable-queue are certainly needed:

commit 19fa81bf1375032cb1a27c7715a28a52b238d4cb
Author: Lennart Poettering <lennart at poettering.net>
Date:   Thu Feb 18 01:54:51 2010 +0100

    pacat: always fully fulfill write requests

    Make sure we always fulfill write requests from the server. If we don't
    the server won't ask us again and playback will stay stuck.


https://tango.0pointer.de/pipermail/pulseaudio-discuss/2010-February/006611.html


and this one (although it's not problematic for playback):

commit b2e9fb6f6e12a3eab8a41c67017507e60d616e2a
Author: Lennart Poettering <lennart at poettering.net>
Date:   Sun Feb 21 21:09:26 2010 +0100

    pacat: pass buffer_attr to recording streams too

    Pointed out by Colin Guthrie.


https://tango.0pointer.de/pipermail/pulseaudio-discuss/2010-February/006698.html






-- 

Colin Guthrie
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http://colin.guthr.ie/

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