[ag-automation] Kernel Summit / RT-Preempt activities in mainline

[Robert Schwebel]

Collegues,

Just a short notice that Linux Weekly News (LWN): 

	http://lwn.net/

has a detailed report about the Linux Kernel Summit that took place in
Ottawa this week. It is in the 20 July edition, currently only available
for paying customers. If you don't happen to be one of them, you'll have
to wait for a week or so before it is available to the general public.
Anyway, consider a subscription, because this is one of the highest
quality news ticker for Linux technology activities.

The most important bits:

- Thomas Gleixner reported about the state of the timer development,
  especially about the dynamic tick code (dyntick): it changes the
  current "one timer tick per HZ" behaviour to "one timer tick if
  necessary", resulting in something like 1.5 ticks per second on a
  "usual" system. Linus noted that there's another dyntick
  implementation for ARM, but it looks like the ARM maintainers are
  willing to adopt the "generic" variant. So Linus sees no reason not
  to merge the dyntick code - good news for the automation folks.

- Ingo Molnar noted that the current RT-Preempt patch decreased to
  something like 700 kB - compared to the 1.6 MB of the still available
  latest 2.6.17-rt7 patch: this shows that tglx and Ingo are doing
  a very successful job in bringing HRT into the mainline. The "big"
  problems are obviously already being resolved, the report talks
  about one outstanding issue: recovery after a realtime task has
  run out of control. The proposed solution is a soft lock detector.

- The patches currently remaining in -rt are mostly hrtimers and
  sleeping locks. Linus seems to have agreed to merge the sleeping locks
  into mainline. Sleeping locks are important to have only a small
  ammount of kernel code to be audited for HRT. 

So the overall situation seems to be excellent! It currently remains
unclear what the state of the architectures (ARM, PPC) currently is, so
stay tuned until after the first 2.6.18-rc based preempt rt patch will
be out. 

Regards,
Robert 
-- 
 Dipl.-Ing. Robert Schwebel | http://www.pengutronix.de
 Pengutronix - Linux Solutions for Science and Industry
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