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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CA+55aFxJHHnEf4nuB5VEKa5OLJ38nY1-tN8oA2JkoYoO6nRUAQ@mail.gmail.com>
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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/