Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753442Ab0H0WMu (ORCPT ); Fri, 27 Aug 2010 18:12:50 -0400 Received: from cantor2.suse.de ([195.135.220.15]:54945 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752580Ab0H0WMt (ORCPT ); Fri, 27 Aug 2010 18:12:49 -0400 From: Petr Tesarik Organization: SUSE LINUX, s.r.o. To: "Luck, Tony" Subject: Re: Serious problem with ticket spinlocks on ia64 Date: Sat, 28 Aug 2010 00:13:18 +0200 User-Agent: KMail/1.9.10 Cc: "linux-ia64@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Hedi Berriche References: <201008271537.35709.ptesarik@suse.cz> <201008272303.34228.ptesarik@suse.cz> <987664A83D2D224EAE907B061CE93D53015D91D45F@orsmsx505.amr.corp.intel.com> In-Reply-To: <987664A83D2D224EAE907B061CE93D53015D91D45F@orsmsx505.amr.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <201008280013.19941.ptesarik@suse.cz> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 885 Lines: 20 On Friday 27 of August 2010 23:11:55 Luck, Tony wrote: > > One more idea. The wrap-around case is the only one when the high word is > > modified. This is in fact the only case when the fetchadd.acq competes > > with the st2.rel about the actual contents of that location. I don't know > > if it matters... > > I pondered that for a while - but I have difficulty believing that > fetchadd looks at which bits changed and only writes back the bytes > that did. OTOH the counter is only 15-bit, so it also wraps around at 0xfffe7fff, but I have never seen it fail there. It always fails after the wrap-around from 0xfffeffff. Petr Tesarik -- 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/