[NTLUG:Discuss] better performance?

[Steve Baker]

Bob Byron wrote:
> 
> > The 'XP' class AMD cpu is for windoz XP, and won in the result when compared
> > with same class cpu on intel's p4. I wonder if it will get the same good
> > result for linux OS. any one tried?
> 
> The XP on an AMD CPU is just a marketing gimick.  You should do great with
> an AMD XP on linux.
> http://www6.tomshardware.com/cpu/02q1/020107/p42200-19.html

...although after what emerged on slashdot yesterday, don't forget to
add 'mem=nopentium' to your LILO options if you use any AGP devices!

> > on the other side, The AMD XP cpu have better performance than intel p4, but
> > it generate more heat than P4. This may be the draw back of the cpu, when
> > you consider to run it for 24/7.
> 
> The XP CPUs use less power and generate less heat then their predecessors, but
> I don't know how it compares to the P4.

...and when the P4 *does* get hot, it halves it's clock rate until it cools
off!  That's a *very* nasty habit!
 
> > Another thought. is 2 cpu computer (for example 2 Celeron 400) will have
> > better performance then one cpu box (1 Celeron 800)?
> 
> As I understand it, the performance boost in a dual cpu operating system is
> when the total output of both CPU's is greater than that which can be
> achieved by one CPU.  Given the choice, I would take the single 800
> because a single application that is not multiprocessor capable will be able
> to run twice as fast where as on a dual 400 system, one CPU would be
> 100% while the other one might be idle.  There are additional factors
> such as throughput on both CPUs vs the single CPU, but I would opt
> for the latter.

You also have to consider the type of application.  If your applications
are memory intensive and are of a nature where cache misses are common
then realise that you now have TWO CPU's fighting over that S-L-O-W
main memory bus.  The memory speed of your motherboard becomes a much
more significant issue when you have multiple processors.

A mobo designed for dual 400MHz CPU's ought to have similar memory
bandwidth to one designed for a *single* 800MHz part...that's rarely
the case though - so you might easily find your dual CPU system running
at half the speed of an 800MHz part *even* when both CPU's are busy at
once.

Also, if you are running something like a game - which is likely to
be CPU intensive - but not be written to use threading - then on a dual
400MHz system, it's going to run at about half the speed it would have
done on a single 800MHz box.

I would always go for a single CPU at twice the speed - all other things
being equal.

----------------------------- Steve Baker -------------------------------
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