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Subject[patch] Real-Time Preemption, -RT-2.6.10-rc1-mm2-V0.7.1

i have released the -V0.7.1 Real-Time Preemption patch, which can be
downloaded from:

this release is mainly a merge of -V0.6.9 to 2.6.10-rc2-mm2.

I havent done a proper changelog for a couple of days so here is a list
of bigger changes since -V0.4:

- implemented a first version of the priority inheritance handling and
priority inversion avoidance logic. This feature, after some initial
stability problems, solved the jackd and rtc_wakeup latencies that
were introduced by the ultra-finegrained locking in the -V series.

(the -T/U series had a coarser locking scheme triggered much lower
levels of priority inversion scenarios. The locking in the -V series
was clearly the tipping point.)

The new PI code covers all synchronization objects in Linux (on
PREEMPT_REALTIME): spinlocks, rwlocks, semaphores and rwsems.
Feedback on the design of this code would be welcome, and patches as
well, if you have a better scheme. The code is pretty modular so feel
free to experiment with alternative schemes.

- completely reworked the debugging framework. All lock types
(spinlocks, rwlocks, semaphores and rwsems) are now tracked, both
their symbolic name and their place of acquire are traced and printed
out upon detection of a deadlock. More and better information is
printed upon a deadlock. Got rid of the 'semaphore owners array' in
debugging mode, this reduces the footprint of semaphores quite
significantly and speeds up deadlock detection.

- got rid of the separate 'counted semaphores' implementation, it was
too intrusive. Made the core 'generic semaphores' implementation
compatible with vanilla Linux counted semaphore semantics. This also
enabled the unrolling of the completion-handling cleanups which,
while being very nice, were getting intrusive as well.

- countless build and driver related reports/fixes from lots of people

- more latency breaks in the remaining critical sections. A
particularly important one was the irqs-off latency bugfix from
Thomas Gleixner.

- sped up the i8259 PIC and the PIT timer hardirq handling routines -
these are now in the path of the longest latency.

- cleaned up IRQ and signal preemption - there were missed
check-rescheds and possibilities for IRQ recursion.

- made ALSA's ioctl()s not use the BKL - this fixes more jackd

to create a -V0.7.1 tree from scratch, the patching order is:

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