[patch] Real-Time Preemption, -VP-2.6.9-rc4-mm1-U1

From: Ingo Molnar
Date: Thu Oct 14 2004 - 09:41:28 EST



i have released the -U1 PREEMPT_REALTIME patch:

http://redhat.com/~mingo/voluntary-preempt/voluntary-preempt-2.6.9-rc4-mm1-U1

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-2.6.9-rc4.bz2
+ http://kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.9-rc4/2.6.9-rc4-mm1/2.6.9-rc4-mm1.bz2
+ http://redhat.com/~mingo/voluntary-preempt/voluntary-preempt-2.6.9-rc4-mm1-U1

Ingo
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