Message-ID: <426D265F.9080902@sfnet.cc>
Date: Mon, 25 Apr 2005 10:18:23 -0700
From: Steve Poe <spoe@sfnet.cc>
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To: "Thomas F.O'Connell" <tfo@sitening.com>
Cc: PgSQL - Performance <pgsql-performance@postgresql.org>
Subject: Re: pgbench Comparison of 7.4.7 to 8.0.2
References: <2784476415a96bb0912ebca41edb3d84@sitening.com>
	<6865.1113600214@sss.pgh.pa.us>
	<b4a298793e5eee60fb12a725197d5c42@sitening.com>
	<426C9508.8030902@sfnet.cc>
	<02c5560a910870da3637b6ff791e3a80@sitening.com>
In-Reply-To: <02c5560a910870da3637b6ff791e3a80@sitening.com>
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Tom,

Just a quick thought: after each run/sample of pgbench, I drop the=20
database and recreate it. When I don't my results become more skewed.

Steve Poe


Thomas F.O'Connell wrote:

> Interesting. I should've included standard deviation in my pgbench=20
> iteration patch. Maybe I'll go back and do that.
>
> I was seeing oscillation across the majority of iterations in the 25=20
> clients/1000 transaction runs on both database versions.
>
> I've got my box specs and configuration files posted. If you see=20
> anything obvious about the tuning parameters that should be tweaked,=20
> please let me know.
>
> Thanks for the feedback!
>
> -tfo
>
> --=20
> Thomas F. O'Connell
> Co-Founder, Information Architect
> Sitening, LLC
>
> Strategic Open Source: Open Your i=E2=84=A2
>
> http://www.sitening.com/
> 110 30th Avenue North, Suite 6
> Nashville, TN 37203-6320
> 615-260-0005
>
> On Apr 25, 2005, at 1:58 AM, Steve Poe wrote:
>
>> >There was some interesting oscillation behavior in both version of=20
>> postgres that occurred with 25 >clients and 1000 transactions at a=20
>> scaling factor of 100. This was repeatable with the distribution=20
>> >version of pgbench run iteratively from the command line. I'm not=20
>> sure how to explain this.
>>
>> Tom,
>>
>> When you see these oscillations, do they occur after so many=20
>> generated results? Some oscillation is normal, in my opinion, from=20
>> 10-15% of the performance is noise-related.
>>
>> The key is to tune the server that you either 1) minimize the=20
>> oscillation and/or 2)increase your overall performance above the=20
>> 10-15% baseline, and 3) find out what the mean and standard deviation=20
>> between all your results.
>>
>> If your results are within that range, this maybe "normal". I=20
>> follow-up with you later on what I do.
>>
>> Steve Poe
>
>
>