Received: from maia.hub.org (unknown [200.46.204.183]) by mail.postgresql.org (Postfix) with ESMTP id A959B633127 for ; Thu, 7 Jan 2010 03:40:17 -0400 (AST) Received: from mail.postgresql.org ([200.46.204.86]) by maia.hub.org (mx1.hub.org [200.46.204.183]) (amavisd-maia, port 10024) with ESMTP id 48748-07 for ; Thu, 7 Jan 2010 07:40:07 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from mail.postnewspapers.com.au (202-89-185-120.static.dsl.amnet.net.au [202.89.185.120]) by mail.postgresql.org (Postfix) with ESMTP id 0D3E8632F30 for ; Thu, 7 Jan 2010 03:40:07 -0400 (AST) Received: from localhost (access [127.0.0.1]) by mail.postnewspapers.com.au (Postfix) with ESMTP id 2710A1E043A; Thu, 7 Jan 2010 15:40:03 +0800 (WST) X-Virus-Scanned: Debian amavisd-new at postnewspapers.com.au Received: from mail.postnewspapers.com.au ([127.0.0.1]) by localhost (access.postnewspapers.com.au [127.0.0.1]) (amavisd-new, port 10024) with LMTP id kIJTBPxknOTw; Thu, 7 Jan 2010 15:40:01 +0800 (WST) Received: from [10.1.1.6] (124-169-133-89.dyn.iinet.net.au [124.169.133.89]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "Craig Ringer", Issuer "POST Certificate Authority" (verified OK)) by mail.postnewspapers.com.au (Postfix) with ESMTPSA id 341601E0439; Thu, 7 Jan 2010 15:40:01 +0800 (WST) Message-ID: <4B458FD0.8020205@postnewspapers.com.au> Date: Thu, 07 Jan 2010 15:40:00 +0800 From: Craig Ringer User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.0; en-GB; rv:1.9.1.5) Gecko/20091204 Thunderbird/3.0 MIME-Version: 1.0 To: Dmitri Girski CC: pgsql-performance@postgresql.org Subject: Re: pg_connect takes 3.0 seconds References: In-Reply-To: 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=0.589 tagged_above=-10 required=5 tests=BAYES_00=-2.599, FH_DATE_PAST_20XX=3.188 X-Spam-Level: X-Archive-Number: 201001/75 X-Sequence-Number: 36955 On 7/01/2010 10:44 AM, Dmitri Girski wrote: > Hi everybody, > > Many thanks to everyone replied, I think we are on the right way. > I've used tcpdump to generate the logs and there are a lot of dropped > packets due to the bad checksum. Network guy is currently looking at the > problem and most likely this is hardware issue. Hang on a sec. You need to ignore bad checksums on *outbound* packets, because many (most?) Ethernet drivers implement some level of TCP offloading, and this will result in packet sniffers seeing invalid checksums for transmitted packets - the checksums haven't been generated by the NIC yet. Unless you know for sure that your NIC doesn't do TSO, ignore bad checksums on outbound packets from the local interface. -- Craig Ringer