Received: from localhost (unknown [200.46.204.182]) by postgresql.org (Postfix) with ESMTP id AF8259FA236 for ; Thu, 13 Sep 2007 14:07:41 -0300 (ADT) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.182]) (amavisd-maia, port 10024) with ESMTP id 68702-05 for ; Thu, 13 Sep 2007 14:07:36 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.5 Received: from lists.commandprompt.com (host-254.commandprompt.net [207.173.203.254]) by postgresql.org (Postfix) with ESMTP id 533179FA103 for ; Thu, 13 Sep 2007 14:07:37 -0300 (ADT) Received: from perhan.alvh.no-ip.org ([190.95.8.15]) (authenticated bits=0) by lists.commandprompt.com (8.13.7/8.13.6) with ESMTP id l8DH7L5t024158; Thu, 13 Sep 2007 10:07:26 -0700 Received: by perhan.alvh.no-ip.org (Postfix, from userid 1000) id 847A047C68; Thu, 13 Sep 2007 13:07:19 -0400 (CLT) Date: Thu, 13 Sep 2007 13:07:19 -0400 From: Alvaro Herrera To: Brad Nicholson Cc: Greg Smith , pgsql-performance@postgresql.org Subject: Re: Long Running Commits - Not Checkpoints Message-ID: <20070913170719.GC1716@alvh.no-ip.org> References: <1189692915.8624.22.camel@bnicholson-desktop> <1189700385.8624.32.camel@bnicholson-desktop> <1189702341.8624.38.camel@bnicholson-desktop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1189702341.8624.38.camel@bnicholson-desktop> User-Agent: Mutt/1.5.16 (2007-06-11) X-Virus-Scanned: ClamAV 0.91.1/4264/Wed Sep 12 23:06:05 2007 on projects.commandprompt.com X-Virus-Status: Clean X-Greylist: Sender succeded SMTP AUTH authentication, not delayed by milter-greylist-1.6 (lists.commandprompt.com [192.168.2.159]); Thu, 13 Sep 2007 10:07:28 -0700 (PDT) X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200709/255 X-Sequence-Number: 26800 Brad Nicholson wrote: > On Thu, 2007-09-13 at 12:19 -0400, Brad Nicholson wrote: > > On Thu, 2007-09-13 at 12:12 -0400, Greg Smith wrote: > > > On Thu, 13 Sep 2007, Brad Nicholson wrote: > > > > > I'd be curious to see how you've got your background writer configured to > > > see if it matches situations like this I've seen in the past. The > > > parameters controlling the all scan are the ones you'd might consider > > > turning down, definately the percentage and possibly the maxpages as well. > > > > > > bgwriter_delay = 50 # 10-10000 milliseconds between > > rounds > > bgwriter_lru_percent = 20.0 # 0-100% of LRU buffers > > scanned/round > > bgwriter_lru_maxpages = 300 # 0-1000 buffers max > > written/round > > bgwriter_all_percent = 20 # 0-100% of all buffers > > scanned/round > > bgwriter_all_maxpages = 600 # 0-1000 buffers max > > written/round > > I should add, there are 6 back ends running on this disk array > (different servers and different data partitions) with these bgwriter > settings. Maybe it is running deferred triggers or something? -- Alvaro Herrera http://www.advogato.org/person/alvherre "I suspect most samba developers are already technically insane... Of course, since many of them are Australians, you can't tell." (L. Torvalds)