RE: Multithreading question

[Christopher Mackie]

>>  I vaguely recall parallel processing as one possible direction for
>> swarm.
>>
>> It seems that the two leading contenders hardware wise are Apple
>> desktops and a P4 system with Hyper Threading, both are multiprocessor setups
>> (albeit virtual in the P4 case).  
 
Just for the record, I'm not aware that Apple is shipping multi-processor 
systems at no upcharge, and there are certainly Intel multi-processor systems 
available (I'm writing this on one).  You can buy them (mine's a Dell), or 
build them (check motherboards.com for multi-processor boards and chip 
suggestions).  They're cheaper than the Apple multi-proc solution, too, 
although that dual-processor XServer really is a beautiful machine.
 
What I've seen about hyperthreading suggests that you'll probably get some 
performance boost without special libraries; how much is never generalizable in 
these cases (hyperthreading is optimized to accelerate Windows API threads, not 
necessarily 3rd party apps).  Whether you can get more boost with a 
hyperthread-aware library I dunno, but I would certainly expect so.
 
Further, not all P4s have hyperthreading: you need the Northwood core 
(Northland? I never can remember).  Anything above 2.3GHz is Northwood, if I 
recall correctly, but below 2.3GHz, machines may be either Northwood or its 
predecessor.  Don't rely on my memory: Intel's site covers the details and how 
to tell.
 
I believe the latest generation Xeon processors (still PIII but optimized for 
serving) also have hyperthreading, but I'm not sure: check the Intel website.  
Next-gen Xeon processors, which will have hyperthreading, are due this quarter, 
by the way, so you might want to delay a purchase 60 days or so.   
 
And just to round out the chip review, AMD is supposed to release its 64-bit 
desktop chip (32-bit apps still run native) sometime this summer.  It's going 
to be a lot more affordable than the Itanium, and the backward compatibility 
will also be a plus, so those of us who need "long longs" and 64-bit 
addressability are looking forward to it very much.  I don't know about 
hyperthreading with the AMD chip, but I suspect not.
 
HTH,  --Chris
 

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