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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:

    http://redhat.com/~mingo/realtime-preempt/

    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
    latencies.

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

    http://kernel.org/pub/linux/kernel/v2.6/linux-2.6.9.tar.bz2
    http://kernel.org/pub/linux/kernel/v2.6/testing/patch-2.6.10-rc1.bz2
    http://kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.10-rc1/2.6.10-rc1-mm2/2.6.10-rc1-mm2.bz2
    http://redhat.com/~mingo/realtime-preempt/realtime-preempt-2.6.10-rc1-mm2-V0.7.1

    Ingo
    -
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