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Real-Time Preemption, -VP-2.6.9-rc4-mm1-U1

From:  Ingo Molnar <mingo@elte.hu>
To:  linux-kernel@vger.kernel.org
Subject:  [patch] Real-Time Preemption, -VP-2.6.9-rc4-mm1-U1
Date:  Thu, 14 Oct 2004 16:31:31 +0200
Cc:  Lee Revell <rlrevell@joe-job.com>, Rui Nuno Capela <rncbc@rncbc.org>, Mark_H_Johnson@Raytheon.com, "K.R. Foley" <kr@cybsft.com>, Daniel Walker <dwalker@mvista.com>, Bill Huey <bhuey@lnxw.com>, Andrew Morton <akpm@osdl.org>, Adam Heath <doogie@debian.org>, Lorenzo Allegrucci <l_allegrucci@yahoo.it>, Dipankar Sarma <dipankar@in.ibm.com>


i have released the -U1 PREEMPT_REALTIME patch:
 
  http://redhat.com/~mingo/voluntary-preempt/voluntary-pree...

this is a strict bugfixes-only release. With -U1 i cannot reproduce any
of the bugs on my testsystems anymore, but take care nevertheless, this
is still experimental code.

Changes since -U0:

 - bugfix: fixed the highmem related crash reported by Adam Heath and i 
   think this could also fix the crash reported by Mark H Johnson.

 - bugfix: fixed a number of networking related soft-lockups, caused by
   a deadlock scenarios in the ipv4, netfilter and net-xmit locking
   code. This could fix the lockup reported by Lorenzo Allegrucci.

 - bugfix: enable interrupts in the int3 handler - gdb will otherwise
   trigger a kernel debug message.

 - cleanup: reworked the RCU API wrappers, we now have the following
   variants:
 
     rcu_read_[un]lock_spin(&spinlock)
     rcu_read_[un]lock_bh_spin(&spinlock)
     rcu_read_[un]lock_sem(&semaphore)

   this change was necessary for the network locking fixes.

 - debugging helper: SysRq-T will now print the stacktrace of currently
   running tasks too. (They might be a bit unreliable occasionally but
   very useful to debug deadlocks.)

 - configurability fix: disabled the /proc/kernel/softirq_preemption and
   hardirq_preemption runtime flags (and the softirq-preempt= and
   hardirq-preempt= boot flags) if PREEMPT_REALTIME is enabled - in the
   fully preemptible model these must always be on.

there are no known bugs at this moment, so please re-report any issues 
you might still encounter.

to create a -U1 tree from scratch the patching order is:

   http://kernel.org/pub/linux/kernel/v2.6/linux-2.6.8.tar.bz2
 + http://kernel.org/pub/linux/kernel/v2.6/testing/patch-2.6...
 + http://kernel.org/pub/linux/kernel/people/akpm/patches/2....
 + http://redhat.com/~mingo/voluntary-preempt/voluntary-pree...

	Ingo
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