Received: from localhost (unknown [200.46.204.184]) by developer.postgresql.org (Postfix) with ESMTP id A77D32E008E for ; Thu, 17 Apr 2008 14:09:19 -0300 (ADT) Received: from developer.postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.184]) (amavisd-maia, port 10024) with ESMTP id 94263-08 for ; Thu, 17 Apr 2008 14:09:08 -0300 (ADT) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.5 Received: from rn-out-0910.google.com (rn-out-0910.google.com [64.233.170.189]) by developer.postgresql.org (Postfix) with ESMTP id 7DBF12E008F for ; Thu, 17 Apr 2008 14:09:10 -0300 (ADT) Received: by rn-out-0910.google.com with SMTP id i24so126190rng.0 for ; Thu, 17 Apr 2008 10:09:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; bh=IzLaeVXwBRQ5fwS7CppRGZjOrqZrRHdU5qoxrYOn4NE=; b=nKlBFuci9VghDP/r7B5ZtoqTpeFm2RpI9xh2AxmUy1yjiJeKV86ZX/btcmadPWdzSCxT8HDUYXr4CvfwebJgAEytZscgabQQgrTLOr4Z0rdp+pCl5rRsndxeNUZq8CS3JVJZ6vVFh/reb8fuVvAwmOgHn2CPgi2r5M0cPEuIEIU= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=Eo7j5zoGZeX/mUekzUlulXE0IzPIwMqawUpnoy5FtaZ9rnucAwdPAlUz6yYmQ50bd66EiXp8IJcq3BIF/WX8MkM3xXzbDZOCEakS5Gw970fGcjIAN3r5bKD74hZOuh9jmt1SJzNvc8sNf4wVCQWoZaVixO2B8fITBdSTychrrCE= Received: by 10.142.226.2 with SMTP id y2mr504116wfg.137.1208452149347; Thu, 17 Apr 2008 10:09:09 -0700 (PDT) Received: by 10.142.185.20 with HTTP; Thu, 17 Apr 2008 10:09:09 -0700 (PDT) Message-ID: Date: Thu, 17 Apr 2008 10:09:09 -0700 From: "Jeffrey Baker" To: "Greg Smith" Subject: Re: Strange behavior: pgbench and new Linux kernels Cc: pgsql-performance@postgresql.org In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200804/244 X-Sequence-Number: 29737 On Thu, Apr 17, 2008 at 12:58 AM, Greg Smith wrote: > So in the case of this simple benchmark, I see an enormous performance > regression from the newest Linux kernel compared to a much older one. This has been discussed recently on linux-kernel. It's definitely a regression. Instead of getting a nice, flat overload behavior when the # of busy threads exceeds the number of CPUs, you get the declining performance you noted. Poor PostgreSQL scaling on Linux 2.6.25-rc5 (vs 2.6.22) http://marc.info/?l=linux-kernel&m=120521826111587&w=2 -jwb