From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8AC6AC433E0 for ; Wed, 12 Aug 2020 19:31:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 732E020658 for ; Wed, 12 Aug 2020 19:31:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726673AbgHLTbK (ORCPT ); Wed, 12 Aug 2020 15:31:10 -0400 Received: from gate.crashing.org ([63.228.1.57]:40508 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726526AbgHLTbK (ORCPT ); Wed, 12 Aug 2020 15:31:10 -0400 Received: from gate.crashing.org (localhost.localdomain [127.0.0.1]) by gate.crashing.org (8.14.1/8.14.1) with ESMTP id 07CJUX3N023473; Wed, 12 Aug 2020 14:30:33 -0500 Received: (from segher@localhost) by gate.crashing.org (8.14.1/8.14.1/Submit) id 07CJUWOw023470; Wed, 12 Aug 2020 14:30:32 -0500 X-Authentication-Warning: gate.crashing.org: segher set sender to segher@kernel.crashing.org using -f Date: Wed, 12 Aug 2020 14:30:32 -0500 From: Segher Boessenkool To: Christophe Leroy Cc: Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , npiggin@gmail.com, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] powerpc/uaccess: Use flexible addressing with __put_user()/__get_user() Message-ID: <20200812193032.GU6753@gate.crashing.org> References: <7b916759-1683-b4df-0d4b-b04b3fcd9a02@csgroup.eu> <878sg6862r.fsf@mpe.ellerman.id.au> <875zb98i5a.fsf@mpe.ellerman.id.au> <8b751738-a9d1-8f55-8f9b-9264c8ac7ed8@csgroup.eu> <0b63e2b8-a134-9a50-2106-8ff110cf9a31@csgroup.eu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0b63e2b8-a134-9a50-2106-8ff110cf9a31@csgroup.eu> User-Agent: Mutt/1.4.2.3i Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 12, 2020 at 02:32:51PM +0200, Christophe Leroy wrote: > Anyway, it seems that GCC doesn't make much use of the "m<>" and the > pre-update form. GCC does not use update form outside of inner loops much. Did you expect anything else? > Most of the benefit of flexible addressing seems to be > achieved with patch 1 ie without the "m<>" constraint and update form. Yes. Segher