Keith Whitwell wrote:
>
> Adam,
>
> I expect the answer is that we need to dig out the old one.
>
> Previously I don't think the full cmpxchg semantics werere required unless the
> box is smp -- there's no case where atomic operations are required for
> hardware interaction, for example. ...
>
> Probably this changed with preempt, though, so we need one even on UP boxes...
>
I can not think of any reason to need a lock or atomic
operation because of preempt. Even the management of the
preempt on/off flags at most requires memory barriers, even
in SMP boxen. Do you have an example?
-- George Anzinger george@mvista.com High-res-timers: http://sourceforge.net/projects/high-res-timers/ Real time sched: http://sourceforge.net/projects/rtsched/ Preemption patch: http://www.kernel.org/pub/linux/kernel/people/rml - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Fri May 31 2002 - 22:00:24 EST