Re: Wierd context-switching issue on Xeon

From: "Anjan Dave" <adave(at)vantage(dot)com>
To: "Josh Berkus" <josh(at)agliodbs(dot)com>, Dirk Lutzebäck <lutzeb(at)aeccom(dot)com>, "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: <pgsql-performance(at)postgreSQL(dot)org>, "Neil Conway" <neilc(at)samurai(dot)com>
Subject: Re: Wierd context-switching issue on Xeon
Date: 2004-04-23 02:27:55
Message-ID: 4BAFBB6B9CC46F41B2AD7D9F4BBAF785098157@vt-pe2550-001.vantage.vantage.com
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Tested the sql on Quad 2.0GHz XEON/8GB RAM:

During the first run, the CS shooted up more than 100k, and was randomly high/low
Second process made it consistently high 100k+
Third brought it down to anaverage 80-90k
Fourth brought it down to an average of 50-60k/s

By cancelling the queries one-by-one, the CS started going up again.

8 logical CPUs in 'top', all of them not at all too busy, load average stood around 2 all the time.

Thanks.
Anjan

-----Original Message-----
From: Josh Berkus [mailto:josh(at)agliodbs(dot)com]
Sent: Tue 4/20/2004 12:59 PM
To: Anjan Dave; Dirk Lutzebäck; Tom Lane
Cc: pgsql-performance(at)postgreSQL(dot)org; Neil Conway
Subject: Re: [PERFORM] Wierd context-switching issue on Xeon

Anjan,

> Quad 2.0GHz XEON with highest load we have seen on the applications, DB
> performing great -

Can you run Tom's test? It takes a particular pattern of data access to
reproduce the issue.

--
Josh Berkus
Aglio Database Solutions
San Francisco

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