[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
Upgrade 1 might not be necessary
Next question - when will I notice the difference in a 512K v. 1M
I guess the *only* application that is pathologically bad is video
I'm assuming this is CPU limited and that the 1M cache is better.
Next question - do the different motherboard chipsets really make much
> David Hopwood <david.nospam.hopwood@REDACTED>
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