From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Poor DBT-3 pgsql 8way numbers on recent 2.6 mm kernels From: Mary Edie Meredith Reply-To: maryedie@osdl.org Content-Type: text/plain Message-Id: <1079130684.2961.134.camel@localhost> Mime-Version: 1.0 Date: Fri, 12 Mar 2004 14:31:25 -0800 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: linux-mm@kvack.org Cc: Mary Edie Meredith List-ID: For the last few mm kernels, I have discovered a performance problem in DBT-3 (using PostgreSQL) in the "throughput" portion of the test (when the test is running multiple processes ) on our 8-way STP systems as compared to 4-way runs and the baseline kernel results. Using the default DBT-3 options (ie using LVM, ext2, PostgreSQL version 7.4.1) on RH9 for 2.6.4-mm1 (PLM 2745) [Note that the 4-way number is _better than the 8-way number] 2.6.4-mm1 Runid..CPUs.Thruput (bigger is better) 289860 8 86.5<-----------(profiling data below) 289831 4 112.7 Compare to base: linux-2.6.4 Runid..CPUs.Thruput 289421 8 137.2<---------- 289383 4 120.73 DBT-3 is a read mostly DSS workload and the throughput phase is where we run multiple query streams (as many as we have CPUs). In this workload, the database is stored on a file system and it almost completely caches in page cache early on. So there is not a lot of physical IO in the throughput portion of the test. I also found similar 8way thruput numbers on these mm kernels: Kernel........PLM..Thruput 2.6.4rc2-mm1 2676 84.56 2.6.4rc1-mm2 2666 85.54 2.6.4rc1-mm1 2664 85.73 Before the 2.6.3-mm4 kernel, the test we are running now (with LVM and pgsql 7.4.1 was not available) so results are not availablewithout running them manually. I did run 2.6.1-mm5and it had a thruput result of 124.02 on an 8way. Still not great but definitely better than ~86.0. I just wanted to report this and I wonder if you already know why this is happening. -------------------------------------------------- Profiling data from RUNID 289860 sorted first by ticks, second by load: http://khack.osdl.org/stp/289860/profile/Framework_Close-tick.sort http://khack.osdl.org/stp/289860/profile/Framework_Close-load.sort -- Mary Edie Meredith maryedie@osdl.org 503-626-2455 x42 Open Source Development Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: aart@kvack.org