On Fri, 2007-07-06 at 15:10 +0100, Rui Nuno Capela wrote:

Hi,

On Wed, July 4, 2007 21:49, Thomas Gleixner wrote:

quoted

I'm pleased to announce the v2.6.21.5-rt19 kernel on behalf of Ingo.


It can be downloaded from the usual place:

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

More info about the -rt patch set can be found in the RT wiki:

http://rt.wiki.kernel.org

Changes since 2.6.21.5-rt18:

- Fixed a nasty and hard to track down slowness / boot problem on SMP
machines with CONFIG_NOHZ enabled. The problem was caused by the timer
wheel base lock held during the get_next_timer_interrupt() call in the
idle path, which eventually led to a bogus PI boosting of the idle task
and in consequence a stale wrong scheduler selection for the affected idle
task.

Kudos to Carsten Emde, who patiently and meticulously isolated the
problem and provided the traces, which allowed to identify the root cause.

Problem solution: Prevent idle task boosting

- back port of the ntp / clock_was_set fix

- integration of the processor_idle fix from Venki Pallipadi, which
resolves boot issues on some platforms

- ep93xx clock events fix from Manfred Gruber

Maybe someone remember me whining about troubles with 2.6.21-rt2..18 on my
Core2 T7200 laptop (fujitsu-siemens amilo i1520).

Althought I'm still with my fingers crossed, I can tell the good news are
that 2.6.21.5-rt19 (and -rt20) does behave far better now on the very same
box.

Yes, it works much better indeed...

Ingo: is there a place where I can read about the changes in different
rtxx releases? What is new/better/fixed in rt20? (I see scheduler stuff
in a diff from rt19 to rt20 but I don't really know what it means). 

-- Fernando

I've more than 8 hours up and running now, without a single glimpse of the
bad symptoms, which used to show in a matter of minutes if not earlier
during init time.

Congratulations. I'm not sure whether this problem can be closed for good,
though, just because you mention the slowness fix applies to CONFIG_NOHZ=Y
and I'm quite sure my badness surged either way.

But at least -rt is usable again here and that just makes me happier :)

Cheers.