High load during audio playback

[Christoph Langner]

Binary package hint: alsa-base

I'm running here Ubuntu Intrepid Beta with all the latest updates installed. I noticed that audio applications create a significant load while playing sound. I've got a FSC Lifebook S-6120, which is using the snd_intel8x0 module to play sounds. When i play a simple mp3 song with Rhythmbox or Quod Libet, these programs cause about 25% usage of my cpu...

$ top
top - 21:43:42 up 4:11, 2 users, load average: 0.57, 0.53, 0.69
Tasks: 134 total, 2 running, 132 sleeping, 0 stopped, 0 zombie
Cpu(s): 34.5%us, 1.6%sy, 0.0%ni, 63.5%id, 0.0%wa, 0.0%hi, 0.3%si, 0.0%st
Mem: 1024312k total, 1006572k used, 17740k free, 37728k buffers
Swap: 3071992k total, 1960k used, 3070032k free, 481680k cached

  PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
20565 me 20 0 137m 44m 21m S 25.4 4.4 0:27.60 rhythmbox
 5833 root 20 0 56312 36m 10m R 4.6 3.6 37:02.45 Xorg
13299 me 20 0 102m 25m 13m S 1.6 2.5 4:24.85 gnome-terminal
[...]

This makes the fan of my laptop spin, causing quite a nouise... When i compare this to Ubuntu Hardy Heron i had about 2-3% load of my audio player and about 20% load of pulseaudio (which i usually deactivate). So playing music caused nearly zero load... The load issue doesn't change, when i set all my audio devices to ALSA in Intrepid

$ lspci | grep Audio
00:1f.5 Multimedia audio controller: Intel Corporation 82801DB/DBL/DBM (ICH4/ICH4-L/ICH4-M) AC'97 Audio Controller (rev 03)
$ uname -ar
Linux stein 2.6.27-4-generic #1 SMP Wed Sep 24 01:30:51 UTC 2008 i686 GNU/Linux

[Luke Yelavich (themuso)]

A couple fo questions. Did you upgrade from hardy using update-manager, or did you do a fresh install of intrepid? Secondly, have you tried using staright pulseaudio? To do so, go into system, preferences, and choose sound, and select either auto detect, or pulseaudio for audio output for playing music.

Thanks.

[Christoph Langner (chrissss)]

> Did you upgrade from hardy using update-manager, or did you do a fresh install of intrepid?

It's a fresh installation of Intrepid.

> Secondly, have you tried using staright pulseaudio? To do so, go into system, preferences, and choose sound, and select either auto detect, or pulseaudio for audio output for playing music.

Yep, no difference.

[Christoph Langner (chrissss)]

I doubt that this bug is a duplicate of bug #73744 since i clearly said, that it doesn't matter if i use alsa or pulseaudio. I know about bug #73744 and experienced the difference in hardy myself, but in hardy i could switch to alsa and the high load was gone... Also in bug #73744 the process pulseaudio itself causes high load, here the application playing sound...

But the latest updates were helpfull. The load while playing music droped normal values

top - 21:23:28 up 1:14, 3 users, load average: 0.43, 0.58, 0.53
Tasks: 140 total, 3 running, 137 sleeping, 0 stopped, 0 zombie
Cpu(s): 14.6%us, 4.0%sy, 0.0%ni, 81.1%id, 0.0%wa, 0.3%hi, 0.0%si, 0.0%st
Mem: 1024428k total, 993888k used, 30540k free, 17552k buffers
Swap: 3071992k total, 1824k used, 3070168k free, 408424k cached

  PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
11272 user 20 0 165m 42m 21m S 11.3 4.2 0:04.00 rhythmbox
 5884 user 20 0 31036 4612 3516 S 5.3 0.5 0:24.02 pulseaudio
 5395 root 20 0 268m 48m 10m S 2.7 4.8 4:09.53 Xorg
...

[Dario Ruellan (druellan)]

I'm also suffering of this bug. Both PulseAudio and Alsa (killall pulseadio) shows high CPU usage while streaming on Rhythmbox and Totem. On OSS CPU values are low and normal.
Please note that is not directly related to Rhythmbox but perhaps to Gstreamer.

[Dario Ruellan (druellan)]

Wondering if this can be related to Alsa's software mixing?
http://www.musicpd.org/forum/index.php?topic=1445.0
http://www.hydrogenaudio.org/forums/lofiversion/index.php/t47591.html