"Luke Lonergan" <llonergan@greenplum.com> writes:
> On 4/7/06 3:02 PM, "Tom Lane" <tgl@sss.pgh.pa.us> 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
