Re: [announce] [patch] ultra-scalable O(1) SMP and UP scheduler

From: Alan Cox (
Date: Sat Jan 05 2002 - 21:30:54 EST

> we can do 32-bit ffz by doing 4x 8-bit ffz's though:

There are better algorithms than the branching one already. You can
do it a 32bit one with a multiply shift and 6 bit lookup if your multiply
is ok, or for non superscalar processors using shift and adds.

64bit is 32bit ffz(x.low|x.high) and a single bit test

I can dig out the 32bit one if need be (its from a NetBSD mailing list)
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