Re: pg 8.1.3, AIX, huge box, painfully slow.

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: "Luke Lonergan" <llonergan(at)greenplum(dot)com>
Cc: "Gavin Hamill" <gdh(at)laterooms(dot)com>, pgsql-performance(at)postgresql(dot)org
Subject: Re: pg 8.1.3, AIX, huge box, painfully slow.
Date: 2006-04-07 22:12:39
Message-ID: 17237.1144447959@sss.pgh.pa.us
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-performance

"Luke Lonergan" <llonergan(at)greenplum(dot)com> writes:
> On 4/7/06 3:02 PM, "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)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

In response to

Browse pgsql-performance by date

  From Date Subject
Next Message Gavin Hamill 2006-04-07 22:27:59 Re: pg 8.1.3, AIX, huge box, painfully slow.
Previous Message Luke Lonergan 2006-04-07 22:06:48 Re: pg 8.1.3, AIX, huge box, painfully slow.