linux-kernel - Re: [RFC][PATCH 0/3] gcc work-around and math128

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Date:	Tue, 24 Apr 2012 14:18:09 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Juri Lelli <juri.lelli@...il.com>
Subject: Re: [RFC][PATCH 0/3] gcc work-around and math128

On Tue, Apr 24, 2012 at 2:15 PM, Andy Lutomirski <luto@...capital.net> wrote:
>
> I played with some of this stuff awhile ago, and for timekeeping, it
> seemed like a 64x32->96 bit multiply followed by a right shift was
> enough, and that operation is a lot faster on 32-bit architectures than
> a full 64x64->128 multiply.

Ack. That may sound like odd numbers, but 64x32->96 sounds sane. And I
think it avoids a multiply even on 64-bit, no?

              Linus
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