Re: [Ngspice-users] Performance problems with Athlon 64 X2?

[gary <li...@la...>]

I'd suggest that someone who knows the workings of nspice come up with 
the test circuit, then we run it on a different machines. I'd assume it 
would make sense to limit this to transient analysis, just to reduce the 
scope.

BTW, I don't recall any flags for multithreading.

John Brunhaver wrote:
> If your gcc flags are not set to take advantage of your specific 
> architecture, you may be leaving performance on the table. 
> 
> Actually, the transition from executing 32-bit to executing 64-bit code 
> is known in some memory intensive applications to cause a reduction in 
> performance due to the increased size of memory addresses and payloads 
> (all else being equal).  At least this was a subject another student at 
> my University was pursuing casually and had shared with me a few months 
> ago.
> 
> However, I have never compiled for or simulated on an AMD machine.  I 
> haven't run extensive simulations yet to compare the run times of 1 
> 64-bit Intel core from a quad-core machine to 1 32-bit P4 thread. Or the 
> comparison of 4-Cores to 2-Threads.
> 
> I would also appreciate anyone's thoughts on this topic.
> 
> On 5/10/07, *Bill Richards* <ric...@tb... 
> <mailto:ric...@tb...>> wrote:
> 
>     Hi-
>     I recently upgraded my simulation system from an old XP 1600+ box to an
>     Athlon 64 X2 3800+.  I grabbed the x86_64 ngspice package via yum, and
>     ran some test cases.  To my surprise, mt test cases ran SLOWER on my new
>     Athlon 64 box!!  Being somewhat paranoid of binary RPMs, I downloaded
>     the sources and necessary libraries and made it all from scratch.  Ran
>     the test cases, and again, the ngspice code on my new box yielded
>     exactly the same results as my old box, only over 2X slower!!!  Has
>     anyone encountered this kind of behavior with ngspice on an Athlon
>     64 box?
>     I don't have any other benchmarks to compare performance of this machine
>     against my now-defunct old machine.  Any help or suggestions would be
>     appreciated!
>     Thanks,
>     -bill-
> 
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