"Luke Lonergan" <llonergan@xxxxxxxxxxxxx> writes: > That said, I find typical memory bandwidth for the P4 in applications is > limited at about 2GB/s. See here for more detail: > http://www.cs.virginia.edu/stream/standard/Bandwidth.html > In fact, looking at the results there, the IBM 650m2 only gets 6GB/s > on all 8 CPUs. I wouldn't be surprised if the strange L3 cache > architecture of the IBM 650 is holding it back from streaming memory > access efficiently. Given Gavin's latest report, I'm wondering how much the IBM slows down when a spinlock operation is involved. If the memory architecture isn't good about supporting serialized access to memory, that gaudy sounding bandwidth number might have little to do with PG's real-world behavior. On the other hand, we already know that Xeons suck about as badly as can be on that same measure; could the pSeries really be worse? regards, tom lane
