From: Bill Findlay <yaldnif.w@blueyonder.co.uk>
Subject: Re: 64 bit codes
Date: Tue, 27 Sep 2011 16:49:34 +0100
Date: 2011-09-27T16:49:34+01:00 [thread overview]
Message-ID: <CAA7AF1E.5E15%yaldnif.w@blueyonder.co.uk> (raw)
In-Reply-To: cec56016-8606-484b-810b-3cdf1e0fcc48@v9g2000vbp.googlegroups.com
On 27/09/2011 15:50, in article
cec56016-8606-484b-810b-3cdf1e0fcc48@v9g2000vbp.googlegroups.com, "Ludovic
Brenta" <ludovic@ludovic-brenta.org> wrote:
> Mok-Kong Shen wrote on comp.lang.ada:
>> For on 64-bit hardware a native 64-bit arithmetic
>> operation shouldn't last very much longer than a corresponding 32-bit
>> opeartion, I would think.
>
> Only a benchmark can tell. It is true that individual 64-bit machine
> instructions are usually just as fast as their 32-bit counterparts but
> 64-bit words use up twice as much memory and, especially, cache memory
> as 32-bit words. The 64-bit ISA has 16 extra registers that may or
> may not compensate for the increased cache pressure and decreased code
> locality in your particular case.
My KDF9 emulator is speeded up by a factor of *more than* two by 64-bit
mode. This is because its integer and logical operands are predominantly
more than 32 bits in size. Pointers are used, but form a negligible part of
the storage space and computational effort.
So, while your caveats are of course valid, there certainly are workloads
that benefit greatly from working in 64 bits.
--
Bill Findlay
with blueyonder.co.uk;
use surname & forename;
next prev parent reply other threads:[~2011-09-27 15:49 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-27 6:59 64 bit codes Mok-Kong Shen
2011-09-27 7:48 ` Georg Bauhaus
2011-09-27 9:04 ` Mok-Kong Shen
2011-09-27 9:14 ` Ludovic Brenta
2011-09-27 9:54 ` Mok-Kong Shen
2011-09-27 10:08 ` Ludovic Brenta
2011-09-27 11:21 ` Mok-Kong Shen
2011-09-27 13:09 ` Ludovic Brenta
2011-09-27 13:25 ` Georg Bauhaus
2011-09-27 13:51 ` Mok-Kong Shen
2011-09-27 14:15 ` Mok-Kong Shen
2011-09-27 14:40 ` Ludovic Brenta
2011-09-27 13:48 ` Mok-Kong Shen
2011-09-27 14:50 ` Ludovic Brenta
2011-09-27 15:49 ` Bill Findlay [this message]
2011-09-28 9:53 ` Georg Bauhaus
2011-09-28 10:36 ` Ludovic Brenta
2011-09-28 0:38 ` Rugxulo
2011-09-29 17:08 ` Rugxulo
2011-09-29 19:20 ` Pascal Obry
2011-09-29 19:26 ` Ludovic Brenta
2011-09-29 19:35 ` Pascal Obry
2011-09-29 19:38 ` Pascal Obry
2011-10-06 2:48 ` mjamesb
2011-09-27 15:39 ` Simon Wright
2011-09-27 19:13 ` Simon Wright
2011-09-28 7:16 ` Georg Bauhaus
2011-09-28 12:26 ` Fritz Wuehler
2011-09-28 13:41 ` Yannick Duchêne (Hibou57)
2011-09-28 14:28 ` Georg Bauhaus
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