Messages in this thread |  | | | Subject | Re: [PATCH] rcutorture: add random preemption | | From | Peter Zijlstra <> | | Date | Mon, 21 Jun 2010 19:06:57 +0200 |
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On Mon, 2010-06-21 at 10:05 -0700, Paul E. McKenney wrote: > On Mon, Jun 21, 2010 at 06:50:11PM +0200, Peter Zijlstra wrote: > > On Mon, 2010-06-21 at 09:43 -0700, Paul E. McKenney wrote: > > > > +#ifdef CONFIG_PREEMPT > > > > + if (!preempt_count() && !(rcu_random(rrsp) % (nrealreaders * 20000))) > > > > + preempt_schedule(); > > > > +#endif > > > > > > This one scared me for a bit -- then I realized that preempt_schedule() > > > won't actually schedule if preemption is in any way disabled. So the > > > above really is OK, because Classic RCU and RCU-bh disable preemption. > > > > > > So, should we have a comment to this effect, or is my hypersensitivity to > > > RCU semantics unique to me? > > > > Well it seems to do a !preempt_count() test too, so I wouldn't worry too > > much about it, still using preempt_schedule() doesn't seem right, why > > not use cond_resched()? > > My guess is that Lai wants to force a call to rcu_sched_qs() even if > !need_resched().
Ah, d'0h yeah, I'm not having the best of days.. monday or something :-)
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