Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750893AbWHCFyb (ORCPT ); Thu, 3 Aug 2006 01:54:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750841AbWHCFyb (ORCPT ); Thu, 3 Aug 2006 01:54:31 -0400 Received: from omx2-ext.sgi.com ([192.48.171.19]:57014 "EHLO omx2.sgi.com") by vger.kernel.org with ESMTP id S1750778AbWHCFya (ORCPT ); Thu, 3 Aug 2006 01:54:30 -0400 Date: Wed, 2 Aug 2006 22:54:17 -0700 (PDT) From: Christoph Lameter To: Andi Kleen cc: virtualization@lists.osdl.org, Jeremy Fitzhardinge , akpm@osdl.org, xen-devel@lists.xensource.com, Chris Wright , Ian Pratt , linux-kernel@vger.kernel.org Subject: Re: [patch 2/8] Implement always-locked bit ops, for memory shared with an SMP hypervisor. In-Reply-To: <200608030739.13334.ak@suse.de> Message-ID: References: <20060803002510.634721860@xensource.com> <200608030725.13713.ak@suse.de> <200608030739.13334.ak@suse.de> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1472 Lines: 37 On Thu, 3 Aug 2006, Andi Kleen wrote: > > I still wonder why you are so focused on ifdefs. Why would we need those? > > Because the Xen drivers will run on a couple of architectures, including > IA64 and PPC. > > If IA64 or PPC didn't implement at least wrappers for the sync ops > then they would all need special ifdefs to handle this. No they would just need to do an #include > > Maybe the best thing would be to have proper atomic ops in UP mode on > > i386? The current way of just dropping the lock bit is the source of the > > troubles. > > It's a huge performance difference. I understand but why dont we use regular ops explicitly instead of hacking the atomic ops. Then we would not have unhack them now. > > Just adding a single line #include to drivers that need > > this functionality is not an undue burden for the drivers that support > > Xen. They have to use special _xxx bitops anyways. > > Ok it could be put into a separate file (although with a neutral name) > > But you would still need to add that to IA64, PPC etc. too, so it > would only avoid adding a single to the other architectures. Could we not just add one fallback definition to asm-generic? - 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/