2.6.19-rc6-rt5

[Ingo Molnar <mingo@elte.hu>]

i've released the 2.6.19-rc6-rt5 tree, which can be downloaded from the 
usual place:

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

the -rt YUM repository for Fedora Core 6 can be activated via:

   cd /etc/yum.repos.d
   wget http://people.redhat.com/~mingo/realtime-preempt/rt.repo
   yum install kernel-rt

on x86_64, do:

   yum install kernel-rt.x86_64

lots of fixes and improvements were done to -rt5. In particular 
SMP/dual-core systems should get quite a bit faster. Changes:

 - implemented proper per-cpu page allocation (PCP-list) in 
   page_alloc.c, for PREEMPT_RT too. (previously this code was #ifdef-ed 
   out and we allocated straight from the zones - but this caused the 
   zone lock to act as a global lock)

 - speedup of PREEMPT_RT's implementation of atomic_dec_and_lock().
   (this was a major bottleneck for workloads like kernel compiles.)

 - more tracer features: symbolic stack backtraces embedded in 
   /proc/latency_trace for certain types of events, switchable syscall 
   tracing.

 - irq-threading cleanups, based on the comments from Sergei Shtylyov, 
   Daniel Walker and Benjamin Herrenschmidt.

 - vsyscall & tracing fixes: 'notsc' should not be required on the YUM 
   rpms anymore.

to build a 2.6.19-rc6-rt5 tree, the following patches should be applied:

  http://kernel.org/pub/linux/kernel/v2.6/linux-2.6.18.tar.bz2
  http://kernel.org/pub/linux/kernel/v2.6/testing/patch-2.6.19-rc6.bz2
  http://redhat.com/~mingo/realtime-preempt/patch-2.6.19-rc6-rt5

as usual, bugreports, fixes and suggestions are welcome,

	Ingo