On Friday 21 December 2007 17:37, Jeff Woods wrote: > > Now, here's what I'm wondering. Is it possible that the source of these > slower benchmarks is that tiny discrepancy between the FSB speed and the > RAM speed? Would there be timing delays in running the memory just > SLIGHTLY slower than the FSB that P95 doesn't much like due to its use > of RAM for the lookup tables?
I very much doubt it. All the current chipsets seem to be very good at optimizing access to RAM even when the FSB and memory access are asynchronous.. > > Or, is it simpler than that? Am I perhaps bumping up against L2 cache > thrashing, something that might be common on Intel multi-core machines > that share a single L2 cache like this? That's certainly possible. BTW what happens if you run two instances? The reason I ask is that it's possible that there is interference between access to main memory on two banks when you're running more than two instances. If this theory is right (as opposed to cache thrashing) then two instances would benchmark just a little bit (one or two percent) slower than one instance, whereas starting a third instance would cause the apparent performance in terms of iteration time to plummet. Regards Brian Beesley _______________________________________________ Prime mailing list [email protected] http://hogranch.com/mailman/listinfo/prime
