Re: [PLUG] Looking to buy new dual-processor system

[Leonard Rosenthol <leonardr@lazerware.com>]

At 5:34 PM -0400 9/18/00, William H. Magill wrote:
>  >   Of course, the real question is... why are you so interested in a dual
> >    processor machine?  What do you plan on doing with it?
>
> This is a very important question.
> You may have very unrealistic expectations.
>
> Does anything you are doing really support multiple processors anyway?

	Good questions and good point.


> SMP is an old technology that nobody seems to get right...still.
> SMP (many hammers) is not the equivilant of  having "a bigger hammer."

	Windows NT/2K does a pretty good job of managing SMP, as does 
the new Mac OS X - and let's not forget all the "big iron" machines 
that have been doing it for a while now.   SMP is still too new for 
Linux and you're right, it's isn't always a benefit.


> But don't forget, these numbers come from Applications that know about
> SMP. Something like 90% of applications will never have any possible reason
> to use the capabilities of SMP. So you are left with the fact that the OS
> probably is running two separate applications at more or less the same time
> - one on each processor.

	This is ONLY true if the OS itself doesn't provide 
kernel-level SMP services to better optimize the processors.


> If you are doing anything with Photoshop or similar graphic or linear
> editing tools, then multiple processors or clusters become a different
> story. Photoshop itself as well as most of its friends have been optomized
> for multiple processor functionality -- the kind of crunching done in a
> "render" is serious fodder for all kinds of hardware parallelism and the
> like.

	Yup!!


> This is one of the reasons that Apple has their dual processor 500mhz
> PowerPC box and why the G4 has the graphics acceleration instructions.
> (These have nothing to do with the display, just rendering.)

	Assuming you mean the Altivec (Velocity Engine) processor, 
that's NOT limited in any way to just graphics - it's an AMAZING 
piece of processor technology that can do some really cool 
optimizations on the right pieces of code.   For example, the most 
popular MP3 product on the Mac (SoundJam) now RIPs MP3's a WHOLE LOT 
FASTER courtesy of Altivec.


> Time sharing can benefit from multiple processors IF things like I/O and
> the like are NOT funneled through one CPU because it owns the driver.

	Right - this gets back to the kernel-level SMP support.



LDR
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Leonard Rosenthol      			Internet:       leonardr@lazerware.com
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