Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753789AbZA0CX5 (ORCPT ); Mon, 26 Jan 2009 21:23:57 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752164AbZA0CXr (ORCPT ); Mon, 26 Jan 2009 21:23:47 -0500 Received: from rv-out-0506.google.com ([209.85.198.234]:16692 "EHLO rv-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751977AbZA0CXq (ORCPT ); Mon, 26 Jan 2009 21:23:46 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type :content-transfer-encoding; b=SGAGcLQR3wUMt6tvaO3qT9uaOLGVOle9/ZkoM1K8r3eO1sjKTExuMiy22UK6uFdWUW E5hxLf20VW+2GjM+iwqAUWsxF/zsg5f00e/70e5cqfaK0735QkNh4j939T1n5SwF9g7Z yDMXlsjiXEy/MUpc1eIslXpkMHp+rQ1ZUGh5E= MIME-Version: 1.0 In-Reply-To: <1232992272.19862.3.camel@londonpacket.bos.redhat.com> References: <1232751312.3990.59.camel@perihelion.bos.jonmasters.org> <20090125225205.GA3783@monkey.beaverton.ibm.com> <1232992272.19862.3.camel@londonpacket.bos.redhat.com> Date: Mon, 26 Jan 2009 21:23:45 -0500 X-Google-Sender-Auth: fc53f2d314709d6d Message-ID: <75b66ecd0901261823o72339347kfa70d6e54f61af00@mail.gmail.com> Subject: Re: [RT] [RFC] simple SMI detector From: Lee Revell To: Jon Masters Cc: Mike Kravetz , linux-rt-users@vger.kernel.org, LKML , williams , "Luis Claudio R. Goncalves" Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1024 Lines: 22 On Mon, Jan 26, 2009 at 12:51 PM, Jon Masters wrote: > On Sun, 2009-01-25 at 14:52 -0800, Mike Kravetz wrote: > >> Any reason why you could not do SMI detection in user level code running >> at the highest RT priority? > > Yeah. I had some suggestions about that already...the problem with that > is that you can't know whether measured latencies are due to SMIs /or/ > other kernel latencies - maybe there's a bug or other problem? I really > want to be able to say to vendors "nope, it's definitely your problem". Can't you do this with a known good version of the -rt kernel and the latency tracer in full RT preempt mode? SMI induced latency will show up in the trace as long delays in random code paths where kernel induced latency can be ruled out. Lee -- 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/