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Subject: Re: [announce] [patch] ultra-scalable O(1) SMP and UP scheduler
To: mingo@elte.hu
Date: Sun, 6 Jan 2002 02:30:54 +0000 (GMT)
Cc: alan@lxorguk.ukuu.org.uk (Alan Cox),
        davidel@xmailserver.org (Davide Libenzi),
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In-Reply-To: <Pine.LNX.4.33.0201060501560.5193-100000@localhost.localdomain> from "Ingo Molnar" at Jan 06, 2002 05:07:47 AM
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From: Alan Cox <alan@lxorguk.ukuu.org.uk>
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> 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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