From owner-freebsd-current@FreeBSD.ORG Tue Feb 14 18:23:38 2006 Return-Path: X-Original-To: freebsd-current@freebsd.org Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 29FBC16A420 for ; Tue, 14 Feb 2006 18:23:38 +0000 (GMT) (envelope-from peterjeremy@optushome.com.au) Received: from mail23.syd.optusnet.com.au (mail23.syd.optusnet.com.au [211.29.133.164]) by mx1.FreeBSD.org (Postfix) with ESMTP id 82AB343D53 for ; Tue, 14 Feb 2006 18:23:37 +0000 (GMT) (envelope-from peterjeremy@optushome.com.au) Received: from turion.vk2pj.dyndns.org (c220-239-19-236.belrs4.nsw.optusnet.com.au [220.239.19.236]) by mail23.syd.optusnet.com.au (8.12.11/8.12.11) with ESMTP id k1EINWRJ011963 (version=TLSv1/SSLv3 cipher=EDH-RSA-DES-CBC3-SHA bits=168 verify=NO); Wed, 15 Feb 2006 05:23:33 +1100 Received: from turion.vk2pj.dyndns.org (localhost.vk2pj.dyndns.org [127.0.0.1]) by turion.vk2pj.dyndns.org (8.13.4/8.13.4) with ESMTP id k1EINWGO003038; Wed, 15 Feb 2006 05:23:32 +1100 (EST) (envelope-from peter@turion.vk2pj.dyndns.org) Received: (from peter@localhost) by turion.vk2pj.dyndns.org (8.13.4/8.13.4/Submit) id k1EINWqt003037; Wed, 15 Feb 2006 05:23:32 +1100 (EST) (envelope-from peter) Date: Wed, 15 Feb 2006 05:23:32 +1100 From: Peter Jeremy To: Vladimir Konrad Message-ID: <20060214182331.GE900@turion.vk2pj.dyndns.org> References: <1139938898.2050.70.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1139938898.2050.70.camel@localhost.localdomain> X-PGP-Key: http://members.optusnet.com.au/peterjeremy/pubkey.asc User-Agent: Mutt/1.5.11 Cc: FreeBSD Current Subject: Re: memtest - an idea X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 14 Feb 2006 18:23:38 -0000 On Tue, 2006-Feb-14 17:41:38 +0000, Vladimir Konrad wrote: >is it viable to have a memtest like process running full-time (low >priority) or scheduled, on running FreeBSD system to discover bad memory >sooner than a later (without taking the system off-line)? If you're using ECC RAM then it's fairly simple to have a background task that reads all memory to detect and scrub single bit errors. If you're looking for something to check non-ECC memory then it's far more difficult. You could write a kernel module that grabbed a free page and did a few tests on it but this won't be able to test allocated memory (keep in mind that the kernel is permanently wired), will miss some pattern sensitive errors and, in the case of pattern sensitive errors, has an equal probablility of causing a failure in a page not being tested. -- Peter Jeremy