From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751747AbZEYLCO (ORCPT ); Mon, 25 May 2009 07:02:14 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751048AbZEYLCA (ORCPT ); Mon, 25 May 2009 07:02:00 -0400 Received: from sg2ehsobe004.messaging.microsoft.com ([207.46.51.78]:3393 "EHLO SG2EHSOBE004.bigfish.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751059AbZEYLB7 convert rfc822-to-8bit (ORCPT ); Mon, 25 May 2009 07:01:59 -0400 X-BigFish: VPS-6(zz1432R98dR1805Mzz1202hzz3198u327alz32i6bh6di61h) X-Spam-TCS-SCL: 0:0 X-WSS-ID: 0KK75AW-02-0QT-01 Date: Mon, 25 May 2009 13:01:47 +0200 From: Borislav Petkov To: "H. Peter Anvin" CC: akpm@linux-foundation.org, greg@kroah.com, mingo@elte.hu, norsk5@yahoo.com, tglx@linutronix.de, mchehab@redhat.com, aris@redhat.com, edt@aei.ca, linux-kernel@vger.kernel.org, Andreas Herrmann Subject: Re: [PATCH 01/22] x86: add methods for writing of an MSR on several CPUs Message-ID: <20090525110147.GB8956@aftab> References: <20090519172449.GB18874@aftab> <4A1392A9.9010609@zytor.com> <20090520144905.GA27991@aftab> <4A147891.5000906@zytor.com> <20090521140800.GA3462@aftab> <4A156361.2040507@zytor.com> <20090521162638.GA10824@aftab> <4A159179.6070607@zytor.com> <20090522143918.GA22850@aftab> <4A16D735.8090104@zytor.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Disposition: inline In-Reply-To: <4A16D735.8090104@zytor.com> User-Agent: Mutt/1.5.18 (2008-05-17) X-OriginalArrivalTime: 25 May 2009 11:01:46.0423 (UTC) FILETIME=[32029470:01C9DD28] Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 22, 2009 at 09:47:49AM -0700, H. Peter Anvin wrote: > Borislav Petkov wrote: > >>> > >> If nothing else it might matter for boot time. Serializing *anything* > >> across a large number of CPUs can be very expensive. > > > > well, upon a closer look, smp_call_function_many() skips over the CPU > > it is executing on and there's currently work in that area to extend > > that API: http://marc.info/?l=linux-kernel&m=123979231511594&w=2. > > > > However, according to Linus' comments, it looks like this would need a > > bit of work so I guess we should wait with the concurrency stuff a bit, > > no? > > > > Well, we can introduce the API now if that's where we intend it to go. Ok, here it is (patches as a reply to that mail). I've added a temporary workaround for smp_call_function_many() not running on the CPU we're on. -- Regards/Gruss, Boris. Operating | Advanced Micro Devices GmbH System | Karl-Hammerschmidt-Str. 34, 85609 Dornach b. München, Germany Research | Geschäftsführer: Thomas M. McCoy, Giuliano Meroni Center | Sitz: Dornach, Gemeinde Aschheim, Landkreis München (OSRC) | Registergericht München, HRB Nr. 43632