From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933025Ab1D0ODn (ORCPT ); Wed, 27 Apr 2011 10:03:43 -0400 Received: from s15228384.onlinehome-server.info ([87.106.30.177]:52668 "EHLO mail.x86-64.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932978Ab1D0ODi (ORCPT ); Wed, 27 Apr 2011 10:03:38 -0400 Date: Wed, 27 Apr 2011 16:03:07 +0200 From: Borislav Petkov To: "Luck, Tony" Cc: "Eric W. Biederman" , Borislav Petkov , Ingo Molnar , "H. Peter Anvin" , Thomas Gleixner , EDAC devel , LKML , Prarit Bhargava , Nagananda Chumbalkar , Russ Anderson Subject: Re: [PATCH -v2 2/2] x86, MCE: Drop the default decoding notifier Message-ID: <20110427140307.GA1704@aftab> References: <20110419171340.GE6640@elte.hu> <20110419173521.GA25374@aftab> <20110419174446.GA13616@elte.hu> <20110420102349.GB1361@aftab> <20110426074238.GA22448@aftab> <20110426214755.GA28314@aftab> <987664A83D2D224EAE907B061CE93D5301C50FD34B@orsmsx505.amr.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <987664A83D2D224EAE907B061CE93D5301C50FD34B@orsmsx505.amr.corp.intel.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 26, 2011 at 07:44:35PM -0400, Luck, Tony wrote: > > Sure. Although any DIMM that is generating so many correctable errors > > that you need to rate limit it in the kernel, won't likely to confine > > itself to correctable errors. > > > > Still it can happen that things are so bad that you do need to rate > > limit it in the kernel. Still with those you start wondering "How did > > this machine boot?" So printk_ratelimit sounds like a fine idea. > > > Perhaps we really want thresholds rather than rate limits (for corrected > errors). One corrected error shouldn't cause any but the most paranoid > to worry. A couple of errors from the same DIMM close together might be > some cause for concern, but could just be happenstance. Enough errors that > rate limiting looks useful, and you are into "something needs to be done" > territory. Right, but for thresholding you need to know to which DIMM the error address belongs. And this is not trivial in all cases. It looks like we need this error reporting thing dynamic: As a sane default, we want to dump some _sensible_ info to syslog about some errors happening. Then, all in-kernel decoding modules can enrich that error info with more specific details. Those two reporting modes should be ratelimited since doing thresholding in kernel could be tricky and taking up precious resources. Finally, you have the userspace daemon which datacenter people or Google with small root partitions could use, which sends that info to a centralized location instead of someone collecting it from each node. In that case, no info goes out to syslog but is eaten up by the RAS daemon which runs on every machine. And in userspace you can do all the cool thresholding, rate limiting, policy applying, etc, your heart desires. Makes sense? -- Regards/Gruss, Boris. Advanced Micro Devices GmbH Einsteinring 24, 85609 Dornach General Managers: Alberto Bozzo, Andrew Bowd Registration: Dornach, Gemeinde Aschheim, Landkreis Muenchen Registergericht Muenchen, HRB Nr. 43632