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

[Raymond Yau]

2010/4/21 Colin Guthrie <gmane at colin.guthr.ie>

> '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
>

is it possible to provide some figure  to compare the CPU usage of PA when
using  pacat, paplay and aplay on your machine ?

the problem of Shuang He seem related to upmixing of stereo to surround71

>>     sink: 0 <alsa_output.pci-0000_00_1b.0.
analog-surround-71>
        volume: 0: 100% 1: 100%
                0: 0.00 dB 1: 0.00 dB
                balance 0.00
        muted: no
        current latency: 444.25 ms
        requested latency: 31.25 ms
        sample spec: s16le 2ch 48000Hz
        channel map: front-left,front-right
                     Stereo
        resample method: speex-float-3
        module: 8
        client: 7 <ALSA plug-in [mplayer_2010_0414]>