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2.6.13-rt6, ktimer subsystem

From:  Ingo Molnar <>
Subject:  2.6.13-rt6, ktimer subsystem
Date:  Tue, 13 Sep 2005 12:00:40 +0200
Cc:  Thomas Gleixner <>, Steven Rostedt <>,, George Anzinger <>

i have released the 2.6.13-rt6 tree, which can be downloaded from the 
usual place:

there are lots of small updates all across and there's a big feature as 
well in this release: a complete rework of the high-resolution timers 
framework, from Thomas Gleixner, called 'ktimers'.

under the ktimer framework the HR (and posix) timers live in a separate 
domain, have their own (per-CPU) rbtree to stay scalable and 
deterministic even with a high number of timers. Another positive effect 
of the introduction of separate ktimers is that kernel/timer.c is now 
using preemptible locks again, removing the cascade() worst-case 
latency. The cleanup factor is high as well: the ktimer framework 
slashes 1300+ lines off the HRT code. See kernel/ktimer.c for details.

the end-effect of ktimers is a much more deterministic HRT engine. The 
original merging of HR timers into the stock timer wheel was a Bad Idea 
(tm). We intend to push the ktimer subsystem upstream as well.

Changes since 2.6.13-rt1:

 - new ktimer subsystem to cleanly implement High Resolution Timers
   (Thomas Gleixner)

 - BKL fix for the new pi-lock code (Steven Rostedt)

 - SMP fix for the new pi-lock code (Steven Rostedt)

 - ALL_TASKS_PI updates (Daniel Walker, Steven Rostedt)

 - trace-irqs fix (Daniel Walker)

 - add raw_irqs_disabled() into the might_sleep() check (Daniel Walker)

 - turned off ALL_TASKS_PI

 - ide_lock updates

 - ioapic build fix

 - HRT build fixes

to build a 2.6.13-rt6 tree, the following patches should be applied:

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