Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756684Ab1CYJ77 (ORCPT ); Fri, 25 Mar 2011 05:59:59 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:40880 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751652Ab1CYJ76 (ORCPT ); Fri, 25 Mar 2011 05:59:58 -0400 Date: Fri, 25 Mar 2011 10:59:31 +0100 From: Ingo Molnar To: Eric Dumazet Cc: Andi Kleen , Linus Torvalds , Jack Steiner , Jan Beulich , Borislav Petkov , Peter Zijlstra , Nick Piggin , "x86@kernel.org" , Thomas Gleixner , Andrew Morton , Ingo Molnar , tee@sgi.com, Nikanth Karthikesan , "linux-kernel@vger.kernel.org" , "H. Peter Anvin" Subject: Re: [PATCH RFC] x86: avoid atomic operation in test_and_set_bit_lock if possible Message-ID: <20110325095931.GA31903@elte.hu> References: <20110324200010.GB7957@elte.hu> <1300999682.2714.23.camel@edumazet-laptop> <20110324205422.GB2393@elte.hu> <1301000557.2714.33.camel@edumazet-laptop> <20110324235654.GM21838@one.firstfloor.org> <1301032040.2714.569.camel@edumazet-laptop> <20110325093228.GB13640@elte.hu> <1301046298.3268.4.camel@edumazet-laptop> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1301046298.3268.4.camel@edumazet-laptop> User-Agent: Mutt/1.5.20 (2009-08-17) X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.3.1 -2.0 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1950 Lines: 49 * Eric Dumazet wrote: > Le vendredi 25 mars 2011 ? 10:32 +0100, Ingo Molnar a ?crit : > > * Eric Dumazet wrote: > > > > > Le vendredi 25 mars 2011 ? 00:56 +0100, Andi Kleen a ?crit : > > > > > never EVER seen any good explanation of why that particular sh*t > > > > > argument would b true. It seems to be purely about politics, where > > > > > some idiotic vendor (namely HP) has convinced Intel that they really > > > > > need it. To the point where some engineers seem to have bought into > > > > > the whole thing and actually believe that fairy tale ("firmware can do > > > > > better" - hah! They must be feeding people some bad drugs at the > > > > > cafeteria) > > > > > > > > For the record I don't think it's a good idea for the BIOS to do > > > > this (and I'm not aware of any engineer who does), > > > > but I think Linux should do better than just disabling PMU use when > > > > this happens. > > > > > > > > However I suspect taking over SCI would cause endless problems > > > > and is very likely not a good idea. > > > > > > I tried many different changes in BIOS and all failed (the machine is > > > damn slow at boot, this takes age). > > > > > > I am stuck :( > > > > Could you please try the patch below? > > This obviously works, [...] Congrats to your now much-improved perf experience! :-) > [...] but you probably need to make a full pass to make sure we dont have a > MSR failure -this should return false in this case. Wanted to keep this patch simple - we are not really hitting MSR failure cases in practice, and by getting the message the user is at least warned that *something* is amiss. Thanks, Ingo -- 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/