[PlanetCCRMA] Re: Sine waves in real time

joey.a joey.a" <joey.a at accelerators.co.uk
Tue Oct 23 18:22:52 2007

> On Sun, 21 Oct 2007 22:29:05 joey.a wrote:
> > > Its a 4 year old amd xp2800. I could run about 140 voices in realtime
> > > 80% cpu usage,
> >
> > Interesting. Your clock is ~ half the speed of Bill's, yet you appear
get ~
> > the same performance, from the same software.
> >
> > Does this mean that AMD is ~twice as efficient as Intel, in music
> > applications, or that Bill has specified for only 50% CPU loading?
> Very much doubt that.  The new Pentium 4s (and Core 2s) have massive
> point units which will easily best an Athlon XP.

I don't see the relevance of that, for practical music applications.

Maximum line signal is 0 db by  convention, and -100 db of noise is pretty
much imperceptible. That equates to an amplitude range of 100,000 to 1.
You can get that with 17 bits.
Even the more basic versions of Fedora are 32 bits, so why would one need
floating point processiong power on top?

Are you saying that the software is squandering processing power by
performing flops, when it could be  doing straight signed multiplications
more efficiently instead?

> I think what we might be
> seeing is the impact of RAM speed.  Scheme is an interpreted language, and
> such will have a large memory footprint (especially Scheme, I think it
> be quite difficult to parse / execute for a computer).  Hence you're going
> find that the process is more "memory bound" (needs to access main
> whereas the highly optimised routines in SC probably fit entirely within
> L2 cache.

That, on the other hand, does make a lot of sense to me.