this might just be "luck" too.  Linux pays no attention to how a
program fits into memory and then into cache.  I've seen significant
performance changes in a program just based on it being run at
different times, and getting a different set of real memory pages
to run in.. sometimes this set of pages maps into the L2 cache
(direct mapped) in a favorable way, the next time it maps into L2
in a poor way.



Robert Hyatt                    Computer and Information Sciences
[EMAIL PROTECTED]               University of Alabama at Birmingham
(205) 934-2213                  115A Campbell Hall, UAB Station 
(205) 934-5473 FAX              Birmingham, AL 35294-1170

On Sun, 22 Nov 1998, Emil Briggs wrote:

> >
> >I am intrigued too. There are vm enhancements in .36 so some paging patterns
> >have no doubt improved but I assure you it doesnt sneak new improved FPU
> >hardware into the pc
> >
> 
> I think the paging stuff could have a big effect on some numeric codes. 
> I've been working on optimizing code for the Origin2000 -- it has
> hardware performance counters and you can see things like the amount of time
> spent in TLB misses. You can run jobs and use different page sizes 
> for data, text and stack and look at the results and there is usually
> an optimum set of values (I've seen 20% variations in performance on
> some stuff that was memory intensive).
> 
> 
> Regards
> Emil
> 

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