#7603 NORM 8.2.0 (: 2.6.25 audio performance regression

Zarro Boogs per Child bugtracker at laptop.org
Fri Aug 1 13:33:51 EDT 2008

#7603: 2.6.25 audio performance regression
   Reporter:  dsd        |       Owner:  dilinger              
       Type:  defect     |      Status:  new                   
   Priority:  normal     |   Milestone:  8.2.0 (was Update.2)  
  Component:  kernel     |     Version:  not specified         
 Resolution:             |    Keywords:  joyride-2181:- 8.2.0:?
Next_action:  never set  |    Verified:  0                     
  Blockedby:             |    Blocking:                        

Comment(by dsaxena):

 Replying to [comment:6 dsd]:

 > > In summary, I don't think this is completely a kernel issue but has to
 do with the way that TamTam, or csound, or the combination is feeding the
 samples to the underlying device.
 > The difference is that TamTam is multitracking; it is interleaved sound.
 ALSA function snd_pcm_write()
 > aplay is just a simple sound stream.

 Looking at an strace, both TamTam and aplay don't call sys_write() to send
 frames to the driver but instead are doing a
 ioctl(SNDRV_PCM_IOCTL_WRITEI_FRAMES); however, both this and sys_write()
 end up calling snd_pcm_lib_write() to the actual write.

 > I guess a sensible place to start attacking this would be to find out
 why hald in update1 does not continually query the battery status. This is
 why we didn't have the more severe crackling before.

 Do you want to look into this while I look into the kernel/tamtam
 interaction? Even with hald running, we should be able to send interleaved
 streams to the device.

Ticket URL: <http://dev.laptop.org/ticket/7603#comment:9>
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