"Luke Lonergan" <llonergan@xxxxxxxxxxxxx> writes: > On 4/7/06 3:02 PM, "Tom Lane" <tgl@xxxxxxxxxxxxx> wrote: >> 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? > I wouldn't be too surprised, but it sounds like it needs a test. Do we have > a test for this? Is there a contention-prone query stream that we can think > up? If you want you could install a pre-8.1 PG and then try one of the queries that we were using as test cases a year ago for spinlock investigations. I don't recall details right now but I remember having posted a pretty trivial test case that would send a multiprocessor machine into context-swap storm, which sounds a whole lot like what Gavin is seeing. I think that 8.1 ought to be relatively free of buffer-manager spinlock contention, which is why I doubt that test case would be interesting against 8.1. The interesting question is what else is he seeing contention for, if it's not the BufMgrLock? regards, tom lane
