Skip site navigation (1) Skip section navigation (2)

Re: Wierd context-switching issue on Xeon patch for 7.4.1

From: Josh Berkus <josh(at)agliodbs(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pg(at)fastcrypt(dot)com
Cc: Paul Tuckfield <paul(at)tuckfield(dot)com>,Anjan Dave <adave(at)vantage(dot)com>, Neil Conway <neilc(at)samurai(dot)com>,Dirk Lutzeb├Ąck <lutzeb(at)aeccom(dot)com>,pgsql-performance(at)postgresql(dot)org
Subject: Re: Wierd context-switching issue on Xeon patch for 7.4.1
Date: 2004-04-22 02:53:24
Message-ID: 200404211953.24898.josh@agliodbs.com (view raw or flat)
Thread:
Lists: pgsql-performance
Tom,

> As far as I can tell, this does reduce the rate of semop's
> significantly, but it does so by bringing the overall processing rate
> to a crawl :-(.  I see 97% CPU idle time when using this patch.
> I believe what is happening is that the select() delay in s_lock.c is
> being hit frequently because the spin loop isn't allowed to run long
> enough to let the other processor get out of the spinlock.

Also, I tested it on production data, and it reduces the CSes by about 40%.  
An improvement, but not a magic bullet.

-- 
Josh Berkus
Aglio Database Solutions
San Francisco

In response to

Responses

pgsql-performance by date

Next:From: Dave CramerDate: 2004-04-22 03:06:41
Subject: Re: Wierd context-switching issue on Xeon patch for 7.4.1
Previous:From: Tom LaneDate: 2004-04-22 02:35:30
Subject: Re: Wierd context-switching issue on Xeon patch for 7.4.1

Privacy Policy | About PostgreSQL
Copyright © 1996-2014 The PostgreSQL Global Development Group