[patch] O(1) scheduler, 2.4.17-A1, 2.5.2-pre7-A1.

From: Ingo Molnar (mingo@elte.hu)
Date: Fri Jan 04 2002 - 12:05:23 EST

this is the next release of the O(1) scheduler:


this release includes fixes and small improvements. (The 2.5.2-A1 patch is
against the 2.5.2-pre7 kernel.) I cannot reproduce any more failures with
this patch, but i couldnt test the vfat lockup problem. The X lockup
problem never occured on any of my boxes, but it might be fixed by one of
the changes included in this patch nevertheless.


 - idle process notification fixes. This fixes the idle=poll breakage
   reported by Anton Blanchard.

 - fix a bug in setscheduler() which crashed if a non-SCHED_OTHER task did
   a setscheduler() call. This fixes the crash reported by Randy Hron. The
   Linux Test Project's syscall tests do not cause a crash anymore.

 - do some more unlikely()/likely() tagging of branches along the hotpath,
   suggested by Jeff Garzik.

 - fix the compile failures in md.c and loop.c and other files, reported
   by many people.

 - fix the too-big-by-one error in the bitmat sizing define, noticed by
   Anton Blanchard.

 - fix a bug in rt_lock() + setscheduler() that had a potential for a
   spinlock lockup.

 - introduce the idle_tick() function, so that idle CPUs can do
   load-balancing as well.

 - do LINUX_VERSION_CODE checking in jffs2 (Jeff Garzik)

 - optimize the big-kernel-lock releasing/acquiring code some more. From
   now on it's absolutely illegal to schedule() from cli()-ed code. (not
   that it was legal.) This moves a few instructions off the scheduler

 - move the ->need_resched setting into idle_init().

 - do not clear RT tasks in reparent_to_init(). There's nothing bad with
   running RT tasks in the background.

 - RT task's priority order was inverted, it should be 0-99, not 99-0.

 - make load-balancing a bit less eager when there are lots of processes
   running: it needs a ~10% imbalance in runqueue lengths to trigger a

 - (there is a small hack in serial.c in the 2.5.2-pre7 patch, to make it

Comments, bug reports, suggestions are welcome,


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