[Off-topic] Re: Build an erlang computer (was:Computers are fast)

Joe Armstrong (AL/EAB) <>
Thu Jan 26 11:30:14 CET 2006


 
> Joe Armstrong (AL/EAB) wrote:
> > I'd like to optimize for
> > 
> >   - compiling programs with a few hundred source code files
> >   - making a high performance web server
> > 
> > Where is my money better spent?
> > 
> >    A cheapish processor with as much memory as possible 
> >    Say a Athlon 64 3000+ 2GHz 512KB cache at 1295 kr
> >    With 4 G memory (about 1000 kr/G)
> > 
> >    Or the cheapest dual core Athlon 64 X2 3800+ 2GH 1MB = 3250kr
> >    With 2 G memory
> > 
> > In the old days I always said that buying more memory was 
> better than 
> > buying a faster processor - is this still true? - also what is the 
> > effect of increasing the size of the processor cache contra 
> more main 
> > memory for the same money?
> 
> For the sake of argument, suppose that the dual core would do 
> everything twice as fast (it certainly won't do better). This 
> will not result in a 2x perceived increase in performance, 
> since most of the things that are being done twice as fast 
> took imperceptible time to begin with.
> 
> It is more effective to remove situations that cause 
> pathologically bad performance -- that is, performance so bad 
> that just doubling the speed won't fix it. One such situation 
> is virtual memory thrashing. The 4G box will be able to do 
> more before running into this problem (and the 64-bit address 
> space allows you to actually make use of 4G).

Good point - I was thinking of the following strategy:

	  Buy a cheapish processor (not dual core) and 2 G memory
        upgrade 1 - If not fast enough add 2 G more memory
	  upgrade 2 - In 18 months change to dual core which will now be
cheap

Upgrade 1 might not be necessary

Next question - when will I notice the difference in a 512K v. 1M
processor cache

I guess the *only* application that is pathologically bad is video
transcoding
I'm assuming this is CPU limited and that the 1M cache is better.

Next question - do the different motherboard chipsets really make much
difference
to performance?

/Joe

		   
          
> 



> --
> David Hopwood <>
> 
> 



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