pulseaudio CPU usage and process name

[Ahmed Kamal]

Hi,
Thanks for the reply. I can confirm terminating firefox brought CPU usage of
pulseaudio down to 0% in top. Also, playing an mp3 through amarok, brought
CPU usage back to 6%. So it seems any playback brings the CPU usage up by
that much!
My sound card is Intel ICH6 chipset ALC861. Is resampling required ? Is it
possible to play at the card's native sample rate to gain back the CPU
cycles, since I almost always have the browser open with Flash in it :/

Regards

On Nov 16, 2007 9:21 PM, Lennart Poettering <mzerqung at 0pointer.de> wrote:

> On Fri, 16.11.07 20:52, Ahmed Kamal (email.ahmedkamal at googlemail.com)
> wrote:
>
> Hi!
>
> > Hi, I'm enjoying the wonders of pulse audio. However, on my centrino
> > 2.0Ghzlaptop, when idle, almost always pulse audio is the most CPU
> > intensive task running, even when I am not playing any audio! It
> > consumes around 6% of CPU competing with firefox! This seems a bit
> > too much to me ?  Also, any idea why the process name appears in top
> > as "exe" rather than pulseaudio!  Regards
>
> The process name issue has been fixed already, but I haven't uploaded
> a new version of PA into Rawhide yet. Also note that this issue is
> alrady listed in rhbz as #345761.
>
> PA closes all devices when idle for more than 1s. Then, CPU
> consumption goes to 0%.
>
> Now, there is a certain piece of software which happens to be
> horrendously broken and is called "Macromedia Flash". I would guess
> that you are using it, aren't you? Now, Flash never closes any
> playback streams until you terminate your browser. Due to that PA
> never considers the device idle and thus never closes the audio device
> and continues to write audio data to it.
>
> Due the closed source nature of Flash this issue is only fixable with
> exceptionally ugly hacks in PA or libflashsupport.so, which I am not
> willing to do.
>
> If PA consumes 6% CPU this is probably because resampling is needed to
> output audio on your device. Resampling is usually the only CPU
> intensive code that is run in PA. While traditionally resampling is
> done in the various media players if you use PA it is done in
> PA. Hence the CPU load will appear as if it was PA's fault, but we
> just moved the resampling work from the app to PA, that's all.
>
> Please terminate your browser, and pause/stop all media players and check
> the CPU load then.
>
> (Some codepaths in PA are not optimized as much as they could of
> course, but from the little information you posted I guessed what I
> wrote above. If you feel that my guess is not correct, then please
> open a bug in rhbz)
>
> Thanks,
>
> Lennart
>
> --
> Lennart Poettering                        Red Hat, Inc.
> lennart [at] poettering [dot] net         ICQ# 11060553
> http://0pointer.net/lennart/           GnuPG 0x1A015CC4
>
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