Messages in this thread | | | Date | Fri, 21 Jun 2002 00:16:18 -0400 | From | Pete Zaitcev <> | Subject | Re: Optimisation for smp_num_cpus loop in hotplug |
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> for (i = 0; i < NR_CPUS; i++) { > if (!cpu_online(i)) > continue; > > Since the cpu online map is probably going to be quite sparse, > could I suggest this alternative, which doesn't have to loop 32 times:
> +#define for_each_cpu(cpu, mask) \ > + for(mask = cpu_online_map; \ > + cpu = __ffs(mask), mask != 0; \ > + mask &= ~(1<<cpu)) > +
This is neat, but I'd like to see it work with O(1) as well. Mingo's code uses some long bitmaps.
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