From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756896Ab1DMHNu (ORCPT ); Wed, 13 Apr 2011 03:13:50 -0400 Received: from ns2.q-leap.de ([88.79.172.217]:55617 "EHLO mail.q-leap.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754607Ab1DMHNt (ORCPT ); Wed, 13 Apr 2011 03:13:49 -0400 Message-ID: <4DA54D2A.3050206@q-leap.de> Date: Wed, 13 Apr 2011 09:13:46 +0200 From: Peter Kruse Organization: Q-Leap Networks GmbH User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.15) Gecko/20110303 Lightning/1.0b2 Thunderbird/3.1.9 MIME-Version: 1.0 To: David Rientjes CC: Christoph Lameter , eric.dumazet@gmail.com, linux-kernel@vger.kernel.org Subject: Re: I have a blaze of 353 page allocation failures, all alike References: <4D53FE43.8030106@q-leap.com> <4D5A2EDB.8060603@q-leap.com> <4D5BC16A.2090205@q-leap.com> <4D5BF56F.1000504@q-leap.com> <4D5CCEED.3010501@q-leap.com> <272bf0cc51439a2ab31ee2f06317dd9f.squirrel@www.q-leap.de> <4D6648B5.1090306@q-leap.com> <4DA4692D.7080207@q-leap.de> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, thanks for your replies, I appreciate that. On 04/13/2011 03:34 AM, David Rientjes wrote: > On Tue, 12 Apr 2011, Christoph Lameter wrote: > >> The problem maybe that you have lots and lots of SCSI devices which >> consume ZONE_DMA memory for their control structures. I guess that is >> oversubscribing the 16M zone. but there are only two devices: # fdisk -l Disk /dev/sda: 249.8 GB, 249865175040 bytes 255 heads, 63 sectors/track, 30377 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Disk identifier: 0x4ac39024 Device Boot Start End Blocks Id System /dev/sda1 1 13 104422 83 Linux /dev/sda2 14 30377 243898830 8e Linux LVM WARNING: GPT (GUID Partition Table) detected on '/dev/sdb'! The util fdisk doesn't support GPT. Use GNU Parted. Disk /dev/sdb: 37946.0 GB, 37946025574400 bytes 255 heads, 63 sectors/track, 4613341 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Disk identifier: 0x00000000 Disk /dev/sdb doesn't contain a valid partition table > You can try to get more memory reserves specifically for lowmem in > ZONE_DMA by changing /proc/sys/vm/lowmem_reserve_ratio. The values are > ratios, so lowering the numbers will yield larger amounts of memory > reserves in ZONE_DMA for GFP_DMA allocations. Try lowering the non-zero > entries to 1 to reserve the entire zone for lowmem, assuming your system > has enough RAM for everything else you're running. this server has 48GB - that should be enough. > This will verify if ZONE_DMA is being depleted from the larger number of > SCSI devices. If you don't get any additional page allocation failures, > then check how much memory in ZONE_DMA is used at peak and that would be a > sane reserve ratio to use next time you restart the system. Could that still be a problem if there are only two scsi devices? Regards, Peter