> > System A: > > CPUs 2 X 500 MHz > > RAM 4 X 128 Meg SDRAM > > Bus 100 MHz > > Timing buffer-cache reads: 128 MB in 0.87 seconds =147.13 MB/sec > > > > System B: > > CPUs 2 X 1000 MHz > > RAM 4 X 256 Meg Registered SDRAM > > Bus 100 MHz > > Timing buffer-cache reads: 524 MB in 2.00 seconds =262.00 MB/sec > > > > Why is system B almost twice as fast? the buffer-cache is measuring systemcall overhead as well as speed of pagecache-to-user-buffer copying. both those are certainly influenced by the CPU speed - even by things like mmx. > > Is registered RAM faster? no, it's inherently slower (mostly latency, but since bursts are short, also in bandwidth.) > Memory interleaving, perhaps? Registered ram has higher latency. It's possible > that the machine is made to do memory interleaving with ECC ram to boost > performance.. sdram means that interleaving is basically irrelevant. interleaving was important when a single bank of ram couldn't sustain one transaction per cycle (EDO, FPM, etc). - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
