Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757950AbZJBRdF (ORCPT ); Fri, 2 Oct 2009 13:33:05 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757740AbZJBRdE (ORCPT ); Fri, 2 Oct 2009 13:33:04 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:38810 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757635AbZJBRdC (ORCPT ); Fri, 2 Oct 2009 13:33:02 -0400 Date: Fri, 2 Oct 2009 19:32:46 +0200 From: Ingo Molnar To: Christoph Lameter Cc: Tejun Heo , akpm@linux-foundation.org, linux-kernel@vger.kernel.org, rusty@rustcorp.com.au, Pekka Enberg , Linus Torvalds Subject: Re: [this_cpu_xx V4 00/20] Introduce per cpu atomic operations and avoid per cpu address arithmetic Message-ID: <20091002173246.GB4884@elte.hu> References: <20091001212521.123389189@gentwo.org> <4AC5C836.8000502@kernel.org> <20091002095455.GC21427@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.5 -1.5 BAYES_00 BODY: Bayesian 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: 1270 Lines: 31 * Christoph Lameter wrote: > On Fri, 2 Oct 2009, Ingo Molnar wrote: > > > One final step/cleanup seems to be missing from it: it should > > replace current uses of percpu_op() [percpu_read(), etc.] in the x86 > > tree and elsewhere with the new this_cpu_*() primitives. > > this_cpu_*() is using per_cpu_from_op/per_cpu_to_op directly, we > > dont need those percpu_op() variants anymore. > > Well after things settle with this_cpu_xx we can drop those. > > > There should also be a kernel image size comparison done for that > > step, to make sure all the new primitives are optimized to the max > > on the instruction level. > > Right. There will be a time period in which other arches will need to > add support for this_cpu_xx first. Size comparison should be only on architectures that support it (i.e. x86 right now). The generic fallbacks might be bloaty, no argument about that. ( => the more reason for any architecture to add optimizations for this_cpu_*() APIs. ) 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/