Real-Time Preemption, -RT-2.6.10-rc1-mm3-V0.7.21 [LWN.net]

From:		Ingo Molnar <mingo@elte.hu>
To:		linux-kernel@vger.kernel.org
Subject:		[patch] Real-Time Preemption, -RT-2.6.10-rc1-mm3-V0.7.21
Date:		Mon, 8 Nov 2004 17:57:18 +0100
Cc:		Lee Revell <rlrevell@joe-job.com>, Rui Nuno Capela <rncbc@rncbc.org>, Mark_H_Johnson@Raytheon.com, "K.R. Foley" <kr@cybsft.com>, Bill Huey <bhuey@lnxw.com>, Adam Heath <doogie@debian.org>, Florian Schmidt <mista.tapas@gmx.net>, Thomas Gleixner <tglx@linutronix.de>, Michal Schmidt <xschmi00@stud.feec.vutbr.cz>, Fernando Pablo Lopez-Lezcano <nando@ccrma.Stanford.EDU>, Karsten Wiese <annabellesgarden@yahoo.de>, Gunther Persoons <gunther_persoons@spymac.com>, emann@mrv.com, Shane Shrybman <shrybman@aei.ca>


i have released the -V0.7.21 Real-Time Preemption patch, which can be
downloaded from the usual place:

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

this release includes fixes and debugging-improvements.

Changes since -V0.7.20:

 - reverted the modlist_lock change - it caused more problems than it 
   solved.

 - implemented irqs-off critical section timing/tracing, inspired by the 
   positive results Thomas Gleixner got with a different kind of cli/sti
   tracer. To activate it, enable CONFIG_CRITICAL_TIMING and 
   CONFIG_CRITICAL_IRQSOFF_TIMING and cli/sti latencies will be reported
   'integrated' into the preempt on/off latencies.

 - sped up tracing in a number of ways. Performance of the tracer slowly
   eroded in the past week or two, it needed alignment and size fixes ,
   inlining/branch-prediction updates and i got rid of unnecessary code.
   The max latency is now traced in cycles - this got rid of an
   expensive 64-bit division in the fastpath. (the /proc/sys tunables
   are still in usecs so userspace should not notice anything.) It's
   still not cheap but roughly 5 times faster than -V0.7.20's tracer, on
   a fast desktop box.

 - renamed CONFIG_PREEMPT_REALTIME to CONFIG_PREEMPT_RT - it's shorter.

 - renamed CONFIG_PREEMPT_TIMING to CONFIG_CRITICAL_TIMING and 
   introduced CONFIG_CRITICAL_IRQSOFF_TIMING to enable cli/sti timing.

to create a -V0.7.21 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...
   http://kernel.org/pub/linux/kernel/people/akpm/patches/2....
   http://redhat.com/~mingo/realtime-preempt/realtime-preemp...

	Ingo
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