Messages in this thread | | | From | Rusty Russell <> | Subject | Re: [PATCH] 2.5.21 Nonlinear CPU support | Date | Tue, 11 Jun 2002 19:09:44 +1000 |
| |
In message <3D05A9E8.FF0DA223@zip.com.au> you write: > and slowdown:
ARGH! STOP IT! I realize it's 'leet to be continually worrying about possible microoptimizations, but I challenge you to *measure* the slowdown between:
> > - for (i = 0; i < smp_num_cpus; i++) { > > - int logical = cpu_logical_map(i);
and
> > + for (i = 0; i < NR_CPUS; i++) { > > + if (!cpu_online(i)) > > + continue;
*Especially* in this context. Sure, a new "max_cpu_number" or "cpu_for_each(i)" macro would fix this, but at the expense of using up additional stack in the reader's brain.
Let's not perpetuate the myth that everything in the kernel needs to be tuned to the last cycle at all costs, hm?
Yes, you stepped on a sore point 8) Rusty. PS. Of course, you know the correct answer, anyway. -- Anyone who quotes me in their sig is an idiot. -- Rusty Russell. - 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/
| |