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Subject[patch] Real-Time Preemption, -RT-2.6.9-mm1-V0.3

i have released the -V0.3 Real-Time Preemption patch, which can be
downloaded from:

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

this is a fixes-only release, but still experimental.

this release should fix a number of bugs that were reported for the V0
series: the futex.c assert, the lockups and the 'slowdown problem'.

The slowdown problem was an architectural issue that surfaced sometime
around U10 and increased in prominence as the the number of mutexes
increased and the number of spinlocks decreased. The futex.c assert was
related to this architectural issue as well, and most of the lockups
reported were i believe livelocks caused by the same issue. Also, the
scheduler path had an easy-to-trigger deadlock that often just silently
locked up.

some of the networking lockups might be related to this issue too, but i
think PREEMPT_REALTIME still has separate lock odering issues within the
networking code. Please re-report any deadlock-tracer asserts that you
might encounter.

Changes since -V0.2:

- HEAP_SIZE fix from Karsten Wiese

- fix hdparm-triggered debugging message reported by Mark H Johnson

- fixed mutex related preemption to not impact the task state, just
like a normal spinlock does. This necessiated the introduction of
TASK_RUNNING_MUTEX handling and related kernel infrastructure. This
framework avoids spurious wakeups done by mutex handling by isolating
the state changes done by normal wakeups vs. the state changes caused
by the mutex code.

- added per-CPU deschedule threads. This fixes a deadlock scenario and
it is also much faster than keventd.

- fix debugging message upon console unblanking

to create a -V0.3 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/people/akpm/patches/2.6/2.6.9/2.6.9-mm1/2.6.9-mm1.bz2
+ http://redhat.com/~mingo/realtime-preempt/realtime-preempt-2.6.9-mm1-V0.3

Ingo
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