[RC5] core questions

Colin L. Hildinger colin at ionet.net
Tue Mar 12 20:06:18 EST 2002


As I recall, the K6 core chips don't have a hardware rotate, it was
implemented with shifts.  The K7 core and the P5 and P6 cores have hardware
rotate.  This is a useful instruction for RC5.  Its usefulness elsewhere has
been debated considerably on this list.  :)

Colin

----- Original Message -----
From: "blitz" <blitz at macronet.net>
To: <rc5 at lists.distributed.net>
Sent: Tuesday, March 12, 2002 6:03 PM
Subject: Re: [RC5] core questions


> Interesting...I'm "assuming" AMD did add the necessary MMX sort of
> instruction set by the time things got to say 233 mhz or so....I recall
> they called it something different than MMX, but it was the same thing.
The
> box I'm on rite now, is a 233 amd, and I know it supports the mmx stuff.
> So despite mmx being a dud  for video, it makes Dnet cores run
> better...great...
> I've always liked the AMD chips because of their risc architecture,
> something I got a bit familiar with when I had a SGI Indy. (wish I still
> had it..heh)
>
>
>
> At 14:45 3/12/02 -0500, you wrote:
>
> >I don't know that the turning of the crunchometere had anything to do
with
> >speed.  But MMX instructions do make a big difference.  Also, certain x86
> >chips didn't have instructions in hardware to do things that we needed to
> >do.  Early AMDs didn't have a rotate instruction that we needed to do,
> >but Intel chips did, they were much faster than AMD chips.  MMX is just
> >integer math handler.
> >
> >
> >
> >
> >On Mon, 11 Mar 2002, blitz wrote:
> >
> > > I just did a processor changeout in a linux box on my lan. I had an
old
> > > cyrix 166 mhz clone chip and replaced it with a pentium P5mmx at the
same
> > > speed. (running Mandrake Linux 8.0 w/64mb memory) I see the core
changed,
> > > and the speed of processing went way up in comparison to the old chip.
The
> > > core running now is a "jasonp" I believe..
> > >
> > > Questions: Is there actually THAT much improvement in handling the RC5
> > task
> > > I should be seeing the little indicator turning that much faster?
> > >
> > > and, does the mmx functions actually contribute something to the
> > processing
> > > speed? I always thought they had something to do with video
processing,
> > not
> > > raw processing power.
> > >
> > > In any case, I want to thank "jasonp" for a core thats visibly more
> > > powerful than the old cyrix one, amazing what just a little tweaking
> > can do huh?
> > >
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> > >
> >
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