Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtp (Exim 4.80) (envelope-from ) id 1XUil4-0004X6-1X for pgsql-performance@arkaria.postgresql.org; Thu, 18 Sep 2014 20:56:54 +0000 Received: from localhost ([127.0.0.1] helo=postgresql.org) by malur.postgresql.org with smtp (Exim 4.80) (envelope-from ) id 1XUil2-0001Cu-NN for pgsql-performance@arkaria.postgresql.org; Thu, 18 Sep 2014 20:56:52 +0000 Received: from magus.postgresql.org ([2a02:c0:301:0:ffff::29]) by malur.postgresql.org with esmtps (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1XUil0-0001Ci-H2 for pgsql-performance@postgresql.org; Thu, 18 Sep 2014 20:56:50 +0000 Received: from mail.catalyst.net.nz ([2404:130:0:10::40:0]) by magus.postgresql.org with esmtp (Exim 4.80) (envelope-from ) id 1XUiku-00076D-91 for pgsql-performance@postgresql.org; Thu, 18 Sep 2014 20:56:48 +0000 Received: from localhost (localhost [127.0.0.1]) by mail.catalyst.net.nz (Postfix) with ESMTP id A9ADF32604; Fri, 19 Sep 2014 08:56:37 +1200 (NZST) X-Virus-Scanned: Debian amavisd-new at catalyst.net.nz Received: from mail.catalyst.net.nz ([127.0.0.1]) by localhost (bertrand.catalyst.net.nz [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id Gz7KceKg1DGJ; Fri, 19 Sep 2014 08:56:36 +1200 (NZST) Received: from [192.168.1.64] (122-62-5-20.jetstream.xtra.co.nz [122.62.5.20]) (Authenticated sender: mark.kirkwood) by mail.catalyst.net.nz (Postfix) with ESMTPSA id 7B37E321E5; Fri, 19 Sep 2014 08:56:36 +1200 (NZST) Message-ID: <541B4704.9090305@catalyst.net.nz> Date: Fri, 19 Sep 2014 08:56:36 +1200 From: Mark Kirkwood User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.1.1 MIME-Version: 1.0 To: Merlin Moncure , "Mkrtchyan, Tigran" CC: postgres performance list Subject: Re: postgres 9.3 vs. 9.4 References: <45142416.42827.1411033201079.JavaMail.zimbra@desy.de> <88549888.42916.1411034301200.JavaMail.zimbra@desy.de> In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Pg-Spam-Score: -2.6 (--) List-Archive: List-Help: List-ID: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: X-Mailing-List: pgsql-performance Precedence: bulk Sender: pgsql-performance-owner@postgresql.org On 19/09/14 08:32, Merlin Moncure wrote: > On Thu, Sep 18, 2014 at 4:58 AM, Mkrtchyan, Tigran > wrote: >> >> 9.3.5: >> 0.035940 END; >> >> >> 9.4beta2: >> 0.957854 END; > > > time being spent on 'END' is definitely suggesting i/o related issues. > This is making me very skeptical that postgres is the source of the > problem. I also thing synchronous_commit is not set properly on the > new instance (or possibly there is a bug or some such). Can you > verify via: > > select * from pg_settings where name = 'synchronous_commit'; > > on both servers? > Yes, does look suspicious. It *could* be that the 9.4 case is getting unlucky and checkpointing just before the end of the 60s run, and 9.3 isn't. > What is iowait? For pci-e SSD, these drives don't seem very fast... > > > These look like rebranded Micron P320's and should be extremely fast...However I note that my Crucial/Micron M550's are very fast for most writes *but* are much slower for sync writes (and fsync) that happen at commit... Cheers Mark -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance