Re: [gentoo-user] [OT]Real compute cycles in a laptop?

[Alan McKinnon <alan@linuxholdings.co.za>]

On Wednesday 08 November 2006 19:00, Mark Knecht wrote:

> The problem with running the neural network app is that it's a huge
> install under Windows. It requires Internet access as it has a
> hardware key that has to be validated against the specific machine.
> Probably takes 1 hour just to set up. Then, once it's set up it takes
> maybe 15 minutes to run a single solution on my older Athlon XP
> 1600+. With that as background I'm sure you can understand that I'm
> not anxious to do it more than once or twice.

OK, scrap that idea

> What I was hoping to do was find some basic way of comparing the
> BogoMIPS on my old Athlon XP machine with BogoMIPS on some new
> machines at the dealer. They haven't had any problems in the past
> with me bringing in a LiveCD and booting Linux. If I could do this
> then I might estimate that the new machine will run the same speed or
> will run 3X the speed when doing these neural network jobs?

For this purpose bogomips is meaningless - it's simply a measure of how 
fast the cpu can execute a very specific and very tight loop and is 
used for some timing setting or other during kernel initialization. 
Bears almost no resemblance to real life operation, other than it's 
safe to say that bogomips goes up as cpu freq goes up

[snip]

> 5) The current Athlon XP Windows machine is busy running Trading
> Solutions but when in Linux I *think* it has a BogoMIPS spec around
> 2800. No way to verify that right now.
>
> It's pretty boring but it seems that you can sort of double the CPU
> MHz spec and come pretty close to the BogoMIPS numbers. However that
> doesn't take cache size into account so maybe BogoMIPS isn't even the
> right thing to be looking at.

bogomips is usually about double the cpu speed, but you can't count on 
that. I would imagine that cache size and fpu performance were 
significant factors.

Let's assume this app of your is floating point intensive (fairly safe 
assumption), and doesn't use a heck of a lot of RAM or disk (already 
shown to be true). So now you need to rate the fpu of the various 
processors and machines around. So I would read reviews of various 
machines in computer performance mags where they publish sane 
benchmarks, to get an idea of what would be best

alan
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