From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Clayton Subject: Re: RAID 5 performance issue. Date: Fri, 5 Oct 2007 20:42:07 +0100 Message-ID: <20071005204207.2d338375@alpha.digital-domain.net> References: <20071003105321.06943824@zeus.pccl.info> <20071003211910.439ded54@alpha.digital-domain.net> <72dbd3150710031336s331782c3yd0ac7ceda4e81774@mail.gmail.com> <20071004150831.6edbf926@zeus.pccl.info> <20071004154441.31addcfe@zeus.pccl.info> <18182.35390.419883.646409@stoffel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <18182.35390.419883.646409@stoffel.org> Sender: linux-raid-owner@vger.kernel.org To: John Stoffel Cc: Justin Piszcz , David Rees , Andrew Clayton , linux-raid@vger.kernel.org List-Id: linux-raid.ids On Fri, 5 Oct 2007 15:02:22 -0400, John Stoffel wrote: > > How much memory does this system have? Have you checked the output of 2GB > /proc/mtrr at all? There' have been reports of systems with a bad $ cat /proc/mtrr reg00: base=0x00000000 ( 0MB), size=2048MB: write-back, count=1 > BIOS that gets the memory map wrong, causing access to memory to slow > down drastically. BIOS-provided physical RAM map: BIOS-e820: 0000000000000000 - 000000000009fc00 (usable) BIOS-e820: 000000000009fc00 - 00000000000a0000 (reserved) BIOS-e820: 00000000000e0000 - 0000000000100000 (reserved) BIOS-e820: 0000000000100000 - 000000007fff0000 (usable) BIOS-e820: 000000007fff0000 - 000000007ffff000 (ACPI data) BIOS-e820: 000000007ffff000 - 0000000080000000 (ACPI NVS) BIOS-e820: 00000000ff780000 - 0000000100000000 (reserved) full dmesg (from 2.6.21-rc8-git2) at http://digital-domain.net/kernel/sw-raid5-issue/dmesg > So if you have 2gb of RAM, try booting with mem=1900m or something Worth a shot. > like that and seeing if things are better for you. > > Make sure your BIOS is upto the latest level as well. Hmm, I'll see whats involved in that. > John Cheers, Andrew