Lee Revell wrote:

> On Sun, 2006-05-21 at 22:24 +0200, Rene Herman wrote:

>> 2.6.17-rc2 (and 3 and 4) make my audio skip. Audio player is ogg123 
>> running in an xterm. Browsing heavy sites (say, eBay) with Firefox 
>> 1.5.0.3 gets me audio underruns quickly. This does not happen on 
>> 2.6.17-rc1 and earlier (I just tested extensively; quite impossible to 
>> generate underruns on -rc1, quickly on -rc2 and later).
>>
>> It's not ALSA; reverted */sound/* from the rc1-rc2 interdiff. It's also 
>> not cfq-iosched.c. Any likely culprits in there? (I'm not a GIT user).
>>
> 
> I would suspect the scheduler interactivity patches.  Please confirm
> this by running ogg123 at nice -20 - do the underruns persist?

They do persist. Thanks for the hint though -- "sched: fix interactive 
task starvation" is the culprit:

http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=5ce74abe788a26698876e66b9c9ce7e7acc25413

Added author and acked-by's to the CC. Mike, this patch is no good for 
me. Audio underruns galore, with only ogg123 and firefox (browsing the 
GIT tree online is also a nice trigger by the way).

If I back it out, everything is fine for me again. Back-out attached as 
a patch against -rc4. This also backs out your follow-up "don't awaken 
RT tasks on expired array" as it was dependant:

http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=8a5bc075b8d8cf7a87b3f08fad2fba0f5d13295e

While looking at the patch I noticed there was +1 difference in the 
"limit" value between the macro and the static inline version of 
expired_starving() so I experimented with adding that back but that 
wasn't it unfortunately.

I can test patches (preferably versus -rc4) although possibly not quickly.

Rene.