Date: Sun, 18 May 2008 12:25:39 -0400 (EDT)
From: Greg Smith <gsmith@gregsmith.com>
To: Matthew <matthew@flymine.org>
cc: pgsql-performance@postgresql.org
Subject: Re: Strange behavior:  pgbench and new Linux kernels
In-Reply-To: <Pine.LNX.4.64.0804181144150.12158@aragorn.flymine.org>
Message-ID: <Pine.GSO.4.64.0805180240590.19416@westnet.com>
References: <Pine.GSO.4.64.0804170230180.26917@westnet.com>
	<Pine.LNX.4.64.0804171538200.20402@aragorn.flymine.org>
	<Pine.LNX.4.64.0804181144150.12158@aragorn.flymine.org>
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On Fri, 18 Apr 2008, Matthew wrote:

> So what happens if you run pgbench on a separate machine to the server? 
> Does the problem still exist in that case?

It does not.  At the low client counts, there's a big drop-off relative to 
running on localhost just because of running over the network.  But once I 
get to 4 clients the remote pgbench setup is even with the localhost one. 
At 50 clients, the all local setup is at 8100 tps while the remote pgbench 
is at 26000.

So it's pretty clear to me now that the biggest problem here is the 
pgbench client itself not working well at all with the newer kernels. 
It's difficult to see through that to tell for sure how well each kernel 
version is handling the server portion of the job underneath.  I hope to 
have time this week to finally submit all this to lkml.

--
* Greg Smith gsmith@gregsmith.com http://www.gregsmith.com Baltimore, MD