From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Mosberger Date: Thu, 29 Jan 2004 19:28:01 +0000 Subject: Re: [RFC/PATCH, 1/4] readX_check() performance evaluation Message-Id: <16409.24257.589224.818006@napali.hpl.hp.com> List-Id: References: <16408.3157.336306.812481@napali.hpl.hp.com> <200401290823.i0T8NTDi024477@mtv-vpn-hw-mfl-2.corp.sgi.com> In-Reply-To: <200401290823.i0T8NTDi024477@mtv-vpn-hw-mfl-2.corp.sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Matthias Fouquet-Lapar Cc: davidm@hpl.hp.com, Andi Kleen , davidm@napali.hpl.hp.com, iod00d@hp.com, ishii.hironobu@jp.fujitsu.com, linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org >>>>> On Thu, 29 Jan 2004 09:23:20 +0100 ("CET), Matthias Fouquet-Lapar said: Matthias> We have done a rather large study with DIMMs that had SBEs Matthias> and have found no evidence that a SBE turns into a UCE, Matthias> i.e. the fact that a SBE is reported, is no indication Matthias> that the device might fail soon. Matthias> As a matter of fact the soft error rates increases while Matthias> parts use smaller process technologies and lower supply Matthias> voltages. Cosmic rays are one source for soft Matthias> errors. Another source are alpha particles emitted by the Matthias> solder. Ehh, wait a second: you're saying that your study proved that if the device isn't failing, it isn't failing. ;-) Of course you'll get noise and perhaps even lots of it due to cosmic rays but this doesn't say anything about the error pattern you when a device _is_ failing (e.g., due to overheating, over-clocking, or wrong voltage). Or did your study cover the cases where a system is operated under "out-of-spec" situation? Matthias> Still I think it's important to log SBEs, but you probably Matthias> will need a treshhold in case you hit a hard SBE. Also Matthias> scrubbing the memory location (and re-read the location to Matthias> check if the error was transient or not) might be a good Matthias> idea if the memory controller supports this. If it is a Matthias> true, hard SBE it should be reported. It also might be a Matthias> good idea to mark the page, so it does not get Matthias> re-allocated. Yes. And once I finally received Andi's earlier mails (guess I have to thank MyDoom for that... ;-( ), it was clear that nobody argued for turning off the error reporting. The issue was only whether or not to log a message via printk() (which, in this case, clearly isn't a good idea). So I think we're all in violent agreement. --david