Real-Time Preemption, -RT-2.6.9-mm1-V0.6.8 [LWN.net]

From:		Ingo Molnar <mingo@elte.hu>
To:		Thomas Gleixner <tglx@linutronix.de>
Subject:		[patch] Real-Time Preemption, -RT-2.6.9-mm1-V0.6.8
Date:		Tue, 2 Nov 2004 16:06:34 +0100
Cc:		Florian Schmidt <mista.tapas@gmx.net>, Lee Revell <rlrevell@joe-job.com>, Paul Davis <paul@linuxaudiosystems.com>, LKML <linux-kernel@vger.kernel.org>, mark_h_johnson@raytheon.com, Bill Huey <bhuey@lnxw.com>, Adam Heath <doogie@debian.org>, Michal Schmidt <xschmi00@stud.feec.vutbr.cz>, Fernando Pablo Lopez-Lezcano <nando@ccrma.stanford.edu>, Karsten Wiese <annabellesgarden@yahoo.de>, jackit-devel <jackit-devel@lists.sourceforge.net>, Rui Nuno Capela <rncbc@rncbc.org>, "K.R. Foley" <kr@cybsft.com>


* Thomas Gleixner <tglx@linutronix.de> wrote:

> > Thomas, can you confirm that this kernel fixes the irqs-off latencies? 
> > (the priority loop indeed was done with irqs turned off.)
> 
> The latencies are still there. I have the feeling it's worse than 0.6.2.

update to others: Thomas debugged this problem today and found the place
that kept irqs disabled for a long time: it was update_process_times(). 
(which i recently touched to break latencies there - but forgot that the
lock is an irqs-off lock!)

i've uploaded a fixed kernel (-V0.6.8) to:

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

(this kernel also has the module-put-unlock-kernel fix that should solve
the other warning reported by Thomas and Bill.)

	Ingo
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