On Mon, 11 Aug 2003, Kris Van Hees wrote: > What you describe is a very common problem with OSes that implement virtual > memory. It's typically pretty much OK when your program's data space fits in > real memory, but once you run beyond that, performance will most definitely > be much worse when your inner loop runs through all the pages. After all, you > are hitting a page fault at a lot of pages, causing major paging activity. > And when the working set itself is generally larger than available real memory, > you end up paging out earlier touched pages in favour of new pages, only to > reverse that again when the next offset loop starts. You just keep cycling > through the pages being swapped in and out. > > As far as I know, no OS with virtual memory has a real solution to this because > there is no way for the OS to know how to solve the problem. It's a bad design > on the programmer's part :) Some performance issues can only be solved by
Or the machine is simply under spec for the job. Who's at fault that Taroon runs like a dog on my Pentium II with 128 Mbytes? Red Hat for a poor package, or me for not adding RAM? The hardware vendor of course! Actually, there's a grain of truth there coz the box does get shirty about mixed SIMM modules. -- Cheers John. Join the "Linux Support by Small Businesses" list at http://mail.computerdatasafe.com.au/mailman/listinfo/lssb Copyright John Summerfield. Reproduction prohibited.
