From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757462AbcIVQHx (ORCPT ); Thu, 22 Sep 2016 12:07:53 -0400 Received: from mail-yb0-f179.google.com ([209.85.213.179]:33473 "EHLO mail-yb0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755506AbcIVQHv (ORCPT ); Thu, 22 Sep 2016 12:07:51 -0400 Date: Thu, 22 Sep 2016 12:07:49 -0400 From: Tejun Heo To: Nicholas Piggin Cc: Christoph Lameter , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH] percpu: improve generic percpu modify-return implementation Message-ID: <20160922160749.GD1892@htj.duckdns.org> References: <20160921085137.862-1-npiggin@gmail.com> <20160921205711.4e804777@roar.ozlabs.ibm.com> <20160921142343.GA10734@htj.duckdns.org> <20160922143500.21809b98@roar.ozlabs.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160922143500.21809b98@roar.ozlabs.ibm.com> User-Agent: Mutt/1.7.0 (2016-08-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Thu, Sep 22, 2016 at 02:35:00PM +1000, Nicholas Piggin wrote: > Well thank you, how about you? Heh, can't complain. Hope to see you around sometime. It's been forever. > Trying a new mail client, sorry. It *seems* to be working now, how's > this? Hmm... Still encoded. > From d0cb9052d6f4c31d24f999b7b0cecb34681eee9b Mon Sep 17 00:00:00 2001 > From: Nicholas Piggin > Date: Wed, 21 Sep 2016 18:23:43 +1000 > Subject: [PATCH] percpu: improve generic percpu modify-return implementations > > Some architectures require an additional load to find the address of > percpu pointers. In some implemenatations, the C aliasing rules do not > allow the result of that load to be kept over the store that modifies > the percpu variable, which causes additional loads. > > Work around this by finding the pointer first, then operating on that. > > It's also possible to mark things as restrict and those kind of games, > but that can require larger and arch specific changes. QP-decoded and applied to percpu/for-4.9. Thanks. -- tejun