From owner-freebsd-arch@FreeBSD.ORG Wed Mar 23 15:57:49 2011 Return-Path: Delivered-To: freebsd-arch@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 7058E1065676 for ; Wed, 23 Mar 2011 15:57:49 +0000 (UTC) (envelope-from freebsd-arch@m.gmane.org) Received: from lo.gmane.org (lo.gmane.org [80.91.229.12]) by mx1.freebsd.org (Postfix) with ESMTP id F0A548FC22 for ; Wed, 23 Mar 2011 15:57:48 +0000 (UTC) Received: from list by lo.gmane.org with local (Exim 4.69) (envelope-from ) id 1Q2QCp-0002lx-2a for freebsd-arch@freebsd.org; Wed, 23 Mar 2011 16:42:43 +0100 Received: from lara.cc.fer.hr ([161.53.72.113]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 23 Mar 2011 16:42:42 +0100 Received: from ivoras by lara.cc.fer.hr with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 23 Mar 2011 16:42:42 +0100 X-Injected-Via-Gmane: http://gmane.org/ To: freebsd-arch@freebsd.org From: Ivan Voras Date: Wed, 23 Mar 2011 16:42:31 +0100 Lines: 33 Message-ID: References: <201103221551.14289.jhb@freebsd.org> <4D88FE89.1060900@feral.com> <4D89DEB9.7060509@freebsd.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Complaints-To: usenet@dough.gmane.org X-Gmane-NNTP-Posting-Host: lara.cc.fer.hr User-Agent: Mozilla/5.0 (X11; U; FreeBSD amd64; en-US; rv:1.9.2.12) Gecko/20101102 Thunderbird/3.1.6 In-Reply-To: <4D89DEB9.7060509@freebsd.org> X-Enigmail-Version: 1.1.2 Subject: Re: kernel memory checks on boot vs. boot time X-BeenThere: freebsd-arch@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussion related to FreeBSD architecture List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 23 Mar 2011 15:57:49 -0000 On 23/03/2011 12:51, Andriy Gapon wrote: > on 22/03/2011 21:54 Matthew Jacob said the following: >> John Baldwin wrote: >>> >>> Do other platforms bother with these sorts of memory tests? If not I'd vote >>> to just drop it. I think this mattered more when you didn't have things like >>> SMAP (so you had to guess at where memory ended sometimes). Also, modern >>> server class x86 machines generally support ECC RAM which will trigger a >>> machine check if there is a problem. I doubt that the early checks are >>> catching anything even for the non-ECC case. >>> >>> If nothing else, I would definitely drop this from amd64 (all those systems >>> have SMAP and machine check support, etc.). >>> >>> >> Memory checks are definitely still useful. Loading the linux mem tester has >> helped find lots of problems, even on so-called modern machines. I'd voter for >> leaving this as an option. > > I think that you talk about a different kind of memory checking/testing. > What we have in FreeBSD looks a lot like what BIOSes use(d) to do on startup. > Besides, AFAIR, it doesn't report any results to you. I'd say that is the main point. At least once I've thought the machine hung when it was doing this check for a surprisingly long time. I'd vote for *at least* adding a "twirling baton" indicator (every 1 GB or so) that something is going on, on all platforms :) If these tests have any effect at all (how can they fail? has anyone seen them fail?) I'd vote to keep them enabled by default, with a tunable to optionally disable them, as every little bit helps for reliability. If there is no effect at all from the tests, then just remove them.