Received: from maia.hub.org (maia-5.hub.org [200.46.204.29]) by mail.postgresql.org (Postfix) with ESMTP id BECDF632679 for ; Wed, 4 Aug 2010 15:51:02 -0300 (ADT) Received: from mail.postgresql.org ([200.46.204.86]) by maia.hub.org (mx1.hub.org [200.46.204.29]) (amavisd-maia, port 10024) with ESMTP id 34446-01 for ; Wed, 4 Aug 2010 18:50:54 +0000 (UTC) X-Greylist: delayed 01:00:00.469176 by SQLgrey-1.7.6 Received: from email.noao.edu (email.noao.edu [140.252.1.54]) by mail.postgresql.org (Postfix) with ESMTP id 8BC256324B6 for ; Wed, 4 Aug 2010 15:50:54 -0300 (ADT) Received: from weaver.tuc.noao.edu ([140.252.14.8] verified) by email.noao.edu (CommuniGate Pro SMTP 5.2.19) with ESMTPS id 71354099; Wed, 04 Aug 2010 10:50:52 -0700 Received: from weaver.tuc.noao.edu (localhost.localdomain [127.0.0.1]) by weaver.tuc.noao.edu (8.13.8/8.13.8) with ESMTP id o74HopZd014826; Wed, 4 Aug 2010 10:50:52 -0700 Message-ID: <4C59A87B.1050005@noao.edu> Date: Wed, 04 Aug 2010 10:50:51 -0700 From: Steve Wampler User-Agent: Thunderbird 2.0.0.24 (X11/20100228) MIME-Version: 1.0 To: John Hasler CC: pgsql-sql@postgresql.org Subject: Re: What does PostgreSQL do when time goes backward? References: <87eiegblzq.fsf@thumper.dhh.gt.org> <20100804125524.GV12093@aart.is.rice.edu> <87wrs671vz.fsf@thumper.dhh.gt.org> In-Reply-To: <87wrs671vz.fsf@thumper.dhh.gt.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=-0.51 tagged_above=-5 required=5 tests=BAYES_05=-0.5, T_RP_MATCHES_RCVD=-0.01 X-Spam-Level: X-Archive-Number: 201008/20 X-Sequence-Number: 34460 John Hasler wrote: > Frank writes: >> My ntp client changes clock (by small amount) at any time: >> Jul 25 05:29:38 bax ntpd[10269]: adjusting local clock by 0.098724s >> Jul 25 05:31:43 bax ntpd[10269]: adjusting local clock by 0.038991s >> Jul 25 06:13:38 bax ntpd[10269]: adjusting local clock by -0.037131s >> Jul 25 15:01:52 bax ntpd[10269]: adjusting local clock by -0.112429s > > Ken writes: >> These do seem to be larger values than you might expect from a clock >> conditioned with ntpd. Is it a VM or is there something going on that >> would stop or suspend your system? > John writes: > There is certainly something wrong there. I saw very bad clock performance on one Linux box I had (dual-single core AMD cpus, no VMs), even with NTP, until I changed the clocksource kernel parameter to hpet. Unfortunately (or fortunately) I no longer have that box. -- Steve Wampler -- swampler@noao.edu The gods that smiled on your birth are now laughing out loud.