Re: [PATCH 1/3] High-res-timers part 1 (core) take 20

george anzinger (george@mvista.com)
Mon, 09 Dec 2002 22:55:45 -0800


Arjan van de Ven wrote:
>
> On Mon, Dec 09, 2002 at 04:27:56AM -0800, george anzinger wrote:
> > >
> > > that's why spinlocks are effectively nops on UP.
> > > What you say is true of just about every spinlock user, and no
> > > they shouldn't all do some IF_SMP() thing; the spinlock itself should be
> > > (and is) zero on UP
> >
> > But with preemption, they really are not nops on UP...
>
> that doesn't justify fuglyfying the kernel code. If you can't live
> with the overhead of preemption, disable preemption. Simple.
> We DON'T want
> spin_lock_nop_on_preempt()
> ...
>
> spin_unlock_nop_on_preempt()
>
> really, I don't, and I can't see anyone else wanting that either

Well, I just thought it was an optimization. I will leave
it the way it is.

-- 
George Anzinger   george@mvista.com
High-res-timers: 
http://sourceforge.net/projects/high-res-timers/
Preemption patch:
http://www.kernel.org/pub/linux/kernel/people/rml
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