[sdiy] SPICE and Processors

[Neil Johnson]

Hi,

George Hearn wrote: 
> I’ve been doing a lot of analogue spice recently and in particular feeding
> audio into the simulation and generating .wav files from probes.

Yeah, Linear Tech's free LTSpice does that too.  A simple way to actually *hear* what you think you're simulating.

> The simulations are incredibly accurate but with a major drawback.. they take
> ages.  10s of audio simulation might take 5 minutes!

If you have a non-trivial circuit they do take time, don't they?

> So here’s the question, would a multi-core processor speed things
> up?  Is a Core 2 Quad 2.8GHz going to run simulations faster than a Core 2
> Duo 3.0GHz or is it clock rate which counts?  Do SPICE simulator engines
> make use of multi-cores?

Weeeelll....  yes a Core 2 Quad 2.8GHz may be faster, but it depends on what you mean by 'faster'.  If you're expecting a doubling due to twice the number of cores, then most likely the answer is 'no'.  You may get some speed up as the extra two cores can run other processes that might otherwise compete for time in a dual-core system.

<Looks to Rainer for a lecture on SIMD...>

As a quick example, running a phaser simulation in version 3 of LTSpice with audio in and out I find a Core 2 Duo 2GHz 2GB machine about 20% faster than a single-core Pentium-M 2GHz 1GB machine (both Dell laptops, WinXP).

> I use Proteus for simulation.

You could check the documentation for Proteus to see if they have written it to use multiple cores, or ask Proteus themselves.  That might give you a more definitive answer.

Neil
--
http://www.njohnson.co.uk