From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763014AbXGFOZ1 (ORCPT ); Fri, 6 Jul 2007 10:25:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753948AbXGFOZT (ORCPT ); Fri, 6 Jul 2007 10:25:19 -0400 Received: from ug-out-1314.google.com ([66.249.92.173]:19207 "EHLO ug-out-1314.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753319AbXGFOZS (ORCPT ); Fri, 6 Jul 2007 10:25:18 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:cc:mime-version:content-type:content-transfer-encoding:content-disposition; b=aqzeyACoJibFhZSGMoKVfByBUtKtIgIG8nzSp/FU3BVT0xmm6ILWlZoe7SX2c9N61VcN+g7ZqUDOD/6nuWIRFg+ahGbMvrBpPK2X3EfptmyDVADku7nihLQlPNmTS7+mRQRXJXcq6NtAUmOeYdwNIO9XO7Ygtmzg5j9x5YOm7Gg= Message-ID: <6278d2220707060725q34005bcfu8f225cf1e3391e61@mail.gmail.com> Date: Fri, 6 Jul 2007 15:25:16 +0100 From: "Daniel J Blueman" To: "Martin Knoblauch" Subject: Re: Understanding I/O behaviour Cc: "Linux Kernel" MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On 5 Jul, 16:50, Martin Knoblauch wrote: > Hi, > > for a customer we are operating a rackful of HP/DL380/G4 boxes that > have given us some problems with system responsiveness under [I/O > triggered] system load. [snip] IIRC, the locking in the CCISS driver was pretty heavy until later in the 2.6 series (2.6.16?) kernels; I don't think they were backported to the 1000 or so patches that comprise RH EL 4 kernels. With write performance being really poor on the Smartarray controllers without the battery-backed write cache, and with less-good locking, performance can really suck. On a total quiescent hp DL380 G2 (dual PIII, 1.13GHz Tualatin 512KB L2$) running RH EL 5 (2.6.18) with a 32MB SmartArray 5i controller with 6x36GB 10K RPM SCSI disks and all latest firmware: # dd if=/dev/cciss/c0d0p2 of=/dev/zero bs=1024k count=1000 509+1 records in 509+1 records out 534643200 bytes (535 MB) copied, 11.6336 seconds, 46.0 MB/s # dd if=/dev/zero of=/dev/cciss/c0d0p2 bs=1024k count=100 100+0 records in 100+0 records out 104857600 bytes (105 MB) copied, 22.3091 seconds, 4.7 MB/s Oh dear! There are internal performance problems with this controller. The SmartArray 5i in the newer DL380 G3 (dual P4 2.8GHz, 512KB L2$) is perhaps twice the read performance (PCI-X helps some) but still sucks. I'd get the BBWC in or install another controller. Daniel -- Daniel J Blueman