#7603 NORM 8.2.0 (: 2.6.25 audio performance regression

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#7603: 2.6.25 audio performance regression
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   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:                        
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Comment(by dsaxena):

 Was looking at the wrong place for the ALSA underrun messages. I ran the
 activity via "sugar-launch TamTamMini" in terminal and grabbed stdin &
 stderr to see the application log. There is definitely a correlation
 between hald running a battery status query and an ALSA underrun occurring
 on both .25 and .22 kernels. I still see underruns when hald is disabled,
 but a drastically smaller number of them and almost unnoticeable to the
 ear. With hald running,
 I'll see several back to back, whereas w/o I'll see maybe one every few
 minutes if that.

 I definitely still hear some crackling w/o hald every so often, but they
 are not related to hald.

 Also, I can run 'aplay <.wav file>' from the command line and not hear any
 issues on both .22 and .25 kernels even if I do:

 {{{
 while true
 do
    cat /sys/devices/platform/olpc-battery.0/power_supply/olpc-battery/*
 done
 }}}

 If I do the above while running TamTamMini, the audio is very crackly and
 there are a lot underruns (again, with both .25 and .22 kernels).

 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.

 I also don't really see much difference in behaviour between .22 and .25.

-- 
Ticket URL: <http://dev.laptop.org/ticket/7603#comment:5>
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