[Bug 45767] Realtime regression in 2.6.15-23

[David Meier]

Public bug reported:

All previous dapper kernels were usable for demanding audio work with
the jack soundsystem. With 2.6.15-23 this does not work anymore.

I checked this with -20, -22 and -23 on two systems with different
soundcards including a high end card (RME Hammerfall) which I am sure
not to be causing the Problem.

With older kernels, jack was perfectly usable even with low latency
settings (2.3 msec) and reported maximum scheduling delays of less than
a msec. With -23, scheduling delays reaches several hundred msecs,
causing corresponding dropouts. This makes the system entirely unusable
for audio work even with rather high latency settings of about 20msec.
Speedstepping was turned off on all systems. Jack claimed to be running
realtime.

I'l be glad to provide more information if requested and help testing
patches or config changes.

** Affects: linux-source-2.6.15 (Ubuntu)
       Severity: Normal
       Priority: (none set)
         Status: Unconfirmed

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Realtime regression in 2.6.15-23
https://launchpad.net/bugs/45767