From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265549AbUBIXsT (ORCPT ); Mon, 9 Feb 2004 18:48:19 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265378AbUBIXou (ORCPT ); Mon, 9 Feb 2004 18:44:50 -0500 Received: from fw.osdl.org ([65.172.181.6]:3782 "EHLO mail.osdl.org") by vger.kernel.org with ESMTP id S265549AbUBIXn4 (ORCPT ); Mon, 9 Feb 2004 18:43:56 -0500 Subject: DBT-3 PostgreSQL performance on 2.6 From: Mary Edie Meredith To: linux-kernel@vger.kernel.org Content-Type: text/plain Organization: Open Source Development Lab Message-Id: <1076370235.3193.644.camel@ibm-e.pdx.osdl.net> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.2.2 Date: 09 Feb 2004 15:43:55 -0800 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org At OSDL we compared the performance of 2.4.24 versus 2.6 base kernels using one of our database workloads, DBT3, on PostgreSQL. (This models a Decision Support type of database, aka 'DSS'). We used the deadline scheduler on 2.6 kernels. DBT-3 has a single stream phase and a multi-stream phase. In the single stream phase a single query runs on the system, whereas the multi-stream phase has an active query per CPU. So we are talking about always a small number of active processes. This workload does not swap on either kernel. It consumes a great deal of memory, and drives a lot of 8k IO's to the disk, mostly read IO. The 2.6 kernels performed better than 2.4.24 for the single stream test, but worse for the multi-stream test for both 4-CPU and 8-CPU systems. Here is the 8-way data (all numbers are percent improvements relative to 2.4.24): 8-way kernel single multi 2.4.24 base base 2.6.2 1.3 -4.26 2.6.1-mm5 0.29 -12.38 2.6.1 6.78 -7.02 2.6.0 7.04 -15.15 Since PostgreSQL does not support direct I/O, we are currently investigating the possibility that system defaults (e.g. vm tuning parameters like dirty_expire_centisec) are not optimal for this workload. Other suggestions welcome. For more data (4-way, AS scheduler, latest 4-way and 8-way runs) see http://developer.osdl.org/maryedie/DBT3_PGSQL/investigation.html For the complete report describing the system layout and workload see: http://developer.osdl.org/maryedie/DBT3_PGSQL/Study_DBT3_PGSQL_wkld.html -- Mary Edie Meredith Test and Performance Group Open Source Development Lab