From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: with ECARTIS (v1.0.0; list xfs); Fri, 10 Aug 2007 12:34:14 -0700 (PDT) Received: from sandeen.net (sandeen.net [209.173.210.139]) by oss.sgi.com (8.12.10/8.12.10/SuSE Linux 0.7) with ESMTP id l7AJY6bm012960 for ; Fri, 10 Aug 2007 12:34:08 -0700 Message-ID: <46BCBDB2.6070703@sandeen.net> Date: Fri, 10 Aug 2007 14:34:10 -0500 From: Eric Sandeen MIME-Version: 1.0 Subject: Re: XFS thread inflation in 2.6.23rc References: <200708081240.21548.ak@suse.de> <200708081422.10373.ak@suse.de> <20070808131404.GQ52011508@sgi.com> <200708081526.06860.ak@suse.de> <20070809110322.GA12413810@sgi.com> In-Reply-To: <20070809110322.GA12413810@sgi.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: xfs-bounce@oss.sgi.com Errors-to: xfs-bounce@oss.sgi.com List-Id: xfs To: David Chinner Cc: Andi Kleen , xfs@oss.sgi.com David Chinner wrote: > Andi, you are complaining to the wrong person about thread counts. I > live in the world of excessive parallelism and multithreaded I/O. I > regularly see 4-8p boxes running hundreds to thousands of I/O > threads on a single filesystem. These are the workloads XFS is > designed for and we optimise for. A single extra thread is noise.... The other thing this is doing, though, is having an impact on power usage, I think. Fedora is trying to identify things which wake the CPU in an effort to reduce power usage if possible. See for example: http://article.gmane.org/gmane.linux.redhat.fedora.testers/50480 quoting: "One of the biggest power problems is apps that wake up the CPU unnecessarily. With the tickless kernel for x86 (and soon x86_64), every time this happens it's a chance for power savings lost. HOW YOU CAN HELP ---------------- We'd like to get as many reports of misbehaving apps as possible. 1) Install the 'powertop' package 2) Run it in a terminal window on a reasonably idle system with your normal combination of apps. (If you run it when you're actively compiling a kernel, watching a movie, or doing other CPU-intensive things, the results aren't as useful.) 3) Note the results..." and here are the results w/ xfs mounted: < Detailed C-state information is only available on Mobile CPUs (laptops) > P-states (frequencies) 2.21 Ghz 0.0% 2.00 Ghz 0.0% 1.80 Ghz 100.0% Wakeups-from-idle per second : 31.7 no ACPI power usage estimate available Top causes for wakeups: 37.0% ( 20.0) mount : xfs_mru_cache_create ... looks like having this running (note: i'm not using filestreams on this mounted filesystem) may be impacting the power usage of the CPU? Or maybe SGI doesn' care about that, if the goal is 100% utilization of these machines on altixes etc... but still - something to consider I think. Thanks, -Eric