Received: from magus.postgresql.org (magus.postgresql.org [87.238.57.229]) by mail.postgresql.org (Postfix) with ESMTP id 707BA23D692 for ; Mon, 23 Jul 2012 09:41:43 -0300 (ADT) Received: from 173-164-140-181-sfba.hfc.comcastbusiness.net ([173.164.140.181] helo=fetter.org) by magus.postgresql.org with esmtp (Exim 4.72) (envelope-from ) id 1StHxE-0003Jc-DM for pgsql-hackers@postgresql.org; Mon, 23 Jul 2012 12:41:42 +0000 Received: from fetter.org (localhost [127.0.0.1]) by fetter.org (Postfix) with ESMTP id 6D4C2300FA5; Mon, 23 Jul 2012 05:41:25 -0700 (PDT) Received: (from shackle@localhost) by fetter.org (8.14.5/8.14.5/Submit) id q6NCfNhT020629; Mon, 23 Jul 2012 05:41:23 -0700 Date: Mon, 23 Jul 2012 05:41:23 -0700 From: David Fetter To: Andrew Dunstan Cc: Tom Lane , Robert Haas , Jeff Janes , pgsql-hackers , Daniel Farina , Craig Ringer , =?iso-8859-1?Q?=22Harold_A=2E_Gim=E9nez=22?= Subject: Re: Checkpointer split has broken things dramatically (was Re: DELETE vs TRUNCATE explanation) Message-ID: <20120723124123.GA20499@fetter.org> References: <11952.1342456591@sss.pgh.pa.us> <13011.1342457859@sss.pgh.pa.us> <15955.1342466333@sss.pgh.pa.us> <9247.1342565810@sss.pgh.pa.us> <20120723043733.GA13020@fetter.org> <500D439C.50608@dunslane.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <500D439C.50608@dunslane.net> User-Agent: Mutt/1.5.21 (2010-09-15) X-Pg-Spam-Score: -0.9 (/) X-Archive-Number: 201207/923 X-Sequence-Number: 211606 On Mon, Jul 23, 2012 at 08:29:16AM -0400, Andrew Dunstan wrote: > > On 07/23/2012 12:37 AM, David Fetter wrote: > >On Tue, Jul 17, 2012 at 06:56:50PM -0400, Tom Lane wrote: > >>Robert Haas writes: > >>>On Mon, Jul 16, 2012 at 3:18 PM, Tom Lane wrote: > >>>>BTW, while we are on the subject: hasn't this split completely > >>>>broken the statistics about backend-initiated writes? > >>>Yes, it seems to have done just that. > >>This implies that nobody has done pull-the-plug testing on either > >>HEAD or 9.2 since the checkpointer split went in (2011-11-01), > >>because even a modicum of such testing would surely have shown that > >>we're failing to fsync a significant fraction of our write traffic. > >> > >>Furthermore, I would say that any performance testing done since > >>then, if it wasn't looking at purely read-only scenarios, isn't > >>worth the electrons it's written on. In particular, any performance > >>gain that anybody might have attributed to the checkpointer splitup > >>is very probably hogwash. > >> > >>This is not giving me a warm feeling about our testing practices. > >Is there any part of this that the buildfarm, or some other automation > >framework, might be able to handle? > > > > I'm not sure how you automate testing a pull-the-plug scenario. I have a dim memory of how the FreeBSD project was alleged to have done it, namely by rigging a serial port (yes, it was that long ago) to the power supply of another machine and randomly cycling the power. > The buildfarm is not at all designed to test performance. That's why > we want a performance farm. Right. Apart from hardware, what are we stalled on? Cheers, David. -- David Fetter http://fetter.org/ Phone: +1 415 235 3778 AIM: dfetter666 Yahoo!: dfetter Skype: davidfetter XMPP: david.fetter@gmail.com iCal: webcal://www.tripit.com/feed/ical/people/david74/tripit.ics Remember to vote! Consider donating to Postgres: http://www.postgresql.org/about/donate