Messages in this thread | | | Date | Wed, 8 Oct 2014 10:00:16 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH 0/1] sched: fix the PREEMPT_ACTIVE check in __trace_sched_switch_state() |
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On Tue, Oct 07, 2014 at 09:50:46PM +0200, Oleg Nesterov wrote: > And note that another caller of task_preempt_count(), set_cpu(), is > fine but it doesn't really need this helper. > > And afaics we do not need ->saved_preempt_count at all, the trivial > patch below makes it unnecessary, we can kill it and all its users. > > Not only this will simplify the code, this will make (well, almost) > the per-cpu preempt counter arch-agnostic. > > Or I missed something?
Two things, per-cpu isn't always faster on some archs, and load-store archs have problems with PREEMPT_NEED_RESCHED, although arguably you can do per-cpu preempt count without that.
> Do you think this makes sense? If yes, I'll try to make the patches.
It penalizes everything but x86 I think. There is no other arch that has per-cpu preempt count atm.
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