Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S275243AbTHMPey (ORCPT ); Wed, 13 Aug 2003 11:34:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S275245AbTHMPey (ORCPT ); Wed, 13 Aug 2003 11:34:54 -0400 Received: from atlrel6.hp.com ([156.153.255.205]:15576 "EHLO atlrel6.hp.com") by vger.kernel.org with ESMTP id S275243AbTHMPeY (ORCPT ); Wed, 13 Aug 2003 11:34:24 -0400 Message-ID: From: "HABBINGA,ERIK (HP-Loveland,ex1)" To: "'linux-kernel@vger.kernel.org'" , "'kens1835@shaw.ca'" Subject: Re: High CPU load with kswapd and heavy disk I/O Date: Wed, 13 Aug 2003 11:34:17 -0400 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.2655.55) Content-Type: text/plain; charset="iso-8859-1" Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2403 Lines: 58 I regularly run the 2.4.21 kernel with 2GB of ram, and I've had to apply Andrew Morton's patch from a year ago that "hunts down buffer heads and kills them": http://marc.theaimsgroup.com/?l=lse-tech&m=102083525007877&w=2 With this patch, kswapd never goes crazy for me anymore. BTW, if you're using NFS (you don't mention it), I've also had great luck improving NFS performance by using Andrea's address space reconfiguration patch: http://www.kernel.org/pub/linux/kernel/people/andrea/kernels/v2.4/2.4.22pre7 aa1/00_3.5G-address-space-5 and selecting the CONFIG_2GB option. This configuration along with 2GB of ram gives me excellent NFS performance. Increasing the system RAM to 4GB with any memory address configuration hurts my performance. The combination of CONFIG_2GB and 2GB of ram has given me the best performance. Note that changing the address space configuration like I've mentioned violates the ABI (http://stage.caldera.com/developer/devspecs/abi386-4.pdf page 47), so your applications might not work as expected. I've also needed to use Neil Brown's "remove the BKL from NFSD" patches, which can be found at: http://cgi.cse.unsw.edu.au/~neilb/patches/linux-stable/?detail=2003-01-06:00 (patches 005 thru 011) Erik On Tue August 12 2003 16:49, Nuno Silva wrote: > My guess is that this is the cause. LOWMEM pressure because of very > large directories... Relating to this, linux-2.6.0-test3-mm1 has Ingo's > 4G/4G memory split. Can you try this kernel, enable 4G/4G feature, and > report back? Something about the 2.6 (and the rmap patched 2.4) kernels causes lockouts on the server -- for reasons OTHER than kswapd. The server running the delete-old-files process runs hundreds of other CPU and disk I/O intensive processes/threads, and it doesn't look like 2.6 is yet able to handle the load. Unfortunately, the server is a production environment machine at a remote site, so lockouts/reboots/kernel panics are baaaad :( I've seen other mentions of kswapd/kupdated problems in 2.4.xx, but few mentions of solutions. Have people just learned to avoid the situations that trigger the mad thrashes? Ken - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/