-----Original Message-----
From: Paul Pettit <[EMAIL PROTECTED]>
To: [EMAIL PROTECTED] <[EMAIL PROTECTED]>
Date: Friday, June 05, 1998 3:15 PM
Subject: RE: $ cat /proc/cpuinfo
>What does this mean? A measure of performance I would assume but you know
>what they say about assuming :). If so what's the rule and can you tell a
>bad chip using this measurement? Or is it just more abitrary numbering?
What
>does any of this mean to Linux/RedHat in terms of performance (if any)?
BogoMIPs isn't a general measure of CPU performance.
It's just a measure of how fast a particular machine (at a given moment,
with a given mix of hardware) performs one simple loop.
It wouldn't be unusual for a "faster" CPU to happen to be a little slower on
the particular instructions involved, yet still give faster performance in
normal use.
It also wouldn't be unusual for a slower RAM subsystem, an unguessable
interaction with other hardware, or cosmic rays to cause the same thing.
Linux has to occasional make use of internal delay loops. Bogomips
determines how long these should be.
If your Bogomips score is incredibly different than other people report with
that same CPU, then you may have a problem, such as your cache being turned
off, CPU clocks set wrong, or turbo button turned off. That's half the
reason they're printed on the screen.
The other half is because Linus thinks it's hilarious when people argue
about Bogomips. :-)
For the record, a Pentium MMX will have around twice the Bogomips of a
Pentium II at a given clock speed. A Pentium at that clock speed will have
around 40% as many as the Pentium MMX.
But the Pentium II is going to outperform the Pentium MMX in normal
operation. Not by a tremendous amount, in the case of similar clock speeds.
The Pentium MMX certainly isn't going to be twice as fast as the Pentium II
at the same clock speed, unless all you're doing is running Bogomips over
and over. :-)
Before you ask, I have no clue why this is. I haven't looked at the
Bogomips code. You can find it, if you've installed the kernal sources, in:
/usr/src/linux/init/main.c.
See the Bogomips mini-howto for more information:
http://www.redhat.com/linux-info/ldp/HOWTO/mini/BogoMips.html
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