Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753289AbXLSI5M (ORCPT ); Wed, 19 Dec 2007 03:57:12 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752051AbXLSI46 (ORCPT ); Wed, 19 Dec 2007 03:56:58 -0500 Received: from py-out-1112.google.com ([64.233.166.177]:64845 "EHLO py-out-1112.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751730AbXLSI45 (ORCPT ); Wed, 19 Dec 2007 03:56:57 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:to:cc:subject:in-reply-to:message-id:references:mime-version:content-type:from; b=KR2HZWoZlquBec+y1iKgq1uPzm2wFralA4aHdsk3hJ8/+X0JZp7UBF+0b2qosM/GcBQBJyZa0ZijgUTu980rumRp285EHAXP30M33UBOc4mL6ov1O/LZ+CrFZmKqSnmInw0flkApJjl+QJYx1bHHjTQwGC0kexg8+uBpBlmCt3U= Date: Wed, 19 Dec 2007 03:56:46 -0500 (EST) To: Nico Schottelius cc: Robert Hancock , LKML Subject: Re: Out of memory and no killable processes: 2.6.22-2-686-bigmem In-Reply-To: <20071219055550.GE21042@denkbrett.schottelius.org> Message-ID: References: <4768692A.3030204@shaw.ca> <20071219055550.GE21042@denkbrett.schottelius.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed From: Parag Warudkar Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2078 Lines: 52 On Wed, 19 Dec 2007, Nico Schottelius wrote: >> If you're running tons of memory, it >> really is better to run a 64-bit kernel if possible. > > Sure? Afaik that results in a bit slower access to memory and appart > from being able to address MUCH more memory doesn't change the > situation. No, generally 64-bit x86 does not slow down things - it might speed things up a bit due to more accessible registers in 64-bit mode. And it does change the situation from VM PoV a lot. In (bearded) God's own words - "... run a 64bit kernel and then the kernel isn't trying the software equivalent of managing a filing cabinet through the keyhole." You will find this recent thread on same topic useful - http://lkml.org/lkml/2007/12/17/7 . > Perhaps I missed something. > > And updating to 64 Bit kernel also implies changing the userland, so > a reinstall would be necessary, wouldn't it? May not be necessary - I recently tried installing Fedora 8 32-bit/PAE on a 8Gb Core 2 box and then upgrading just the kernel to 64-bit and it worked fine except for the 32-bit iptables service having problems running on 64-bit kernel. [Also I hear the closed source nVidia binaries will not work on this setup - so if you don't need such things you will be able to go to a 64-bit kernel w/o reinstalling userspace.] >> I believe there are >> some cases where low memory can be pretty easily exhausted on machines with >> lots of high memory. > > Some minutes ago the third machine of that type freezed. > with 7 GiB of *free* memory, before getting oom+panic. > > Is it possible to debug this issue somehow? Like said in the above thread I referred to you might have better luck with RHEL/CentOS or other "Enterprise" kernels if you want to stick to 32-bit. But the pain is not worthwhile - give 64-bit kernel a shot. HTH Parag -- 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/