2007/6/28, Daniel Gryniewicz <[EMAIL PROTECTED]>:
On Thu, 2007-06-28 at 18:45 +0200, Dieter Ries wrote: > Hi, > > > Hemmann, Volker Armin schrieb: > > On Donnerstag, 28. Juni 2007, Simon Cooper wrote: > >> whats with the NUMA stuff? > > > > nothing. If you only have once cpu with two cores, don't use it! > > What exactly does that mean? None of those : > > [*] Non Uniform Memory Access (NUMA) Support > [*] Old style AMD Opteron NUMA detection > [*] ACPI NUMA detection > [*] NUMA emulation > > Or should one use the emulation. > > And is it suggested not to use NUMA only on amd cpu's, or is it just the > same on core2duo processors? >
numa is a way of using the integrated dma ram controllers of amd64 cpus.... on intel systems they are useless if you don't have a lot of cpus....
BTW, what is NUMA exactly? And when should one use it? > Intel CPUs don't do NUMA, only AMD cpus do. However, you need at least 2 physical CPUs to actually do NUMA, and you also need memory attached to each one. Most cheap dual CPU AMD boards don't actually have memory hooked to both CPUs, only to one of them. If your board has banks of ram (generally on either side of the CPUs) it probably does NUMA. Otherwise, it doesn't. That said, enabling NUMA on a non-NUMA box doesn't really hurt, same as enabling SMP on a non-SMP box.
of what i have experienced on my amd64x2 4800 i had little performance boost when i used numa compiled.... for what i know on the amd x2 cpus every core has its own l2 chache, its own 64bit ddr mem controller and a unique l3 cache.... i have learned that the numa helps the overall system performance by using in a better way the integrated mem controller and not only by working as you said, but i may be wrong.... the only fact that i've experienced on my desktop is that i have a little perfomance boost.... it may be due to the mb, an Asus M2N-SLI Deluxe AiLifestyle Series.... Daniel
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