From mboxrd@z Thu Jan  1 00:00:00 1970
From: Pavel Machek <pavel@ucw.cz>
Date: Fri, 12 Jul 2002 12:39:15 +0000
Subject: [Linux-ia64] Re: O(1) scheduler "complex" macros
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To: linux-ia64@vger.kernel.org

Hi!

> >  #define task_running(rq, p) \
> > 	((rq)->curr = (p)) && !spin_is_locked(&(p)->switch_lock)
> 
> one more implementational note: the above test is not 'sharp' in the sense
> that on SMP it's only correct (the test has no barriers) if the runqueue
> lock is held. This is true for all the critical task_running() uses in
> sched.c - and the cases that use it outside the runqueue lock are
> optimizations so they dont need an exact test.

I believe this is worth a *big fat* comment.
								Pavel
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