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=-5.2 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 13070C432BE for ; Tue, 24 Aug 2021 15:32:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E767C61357 for ; Tue, 24 Aug 2021 15:32:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238360AbhHXPdZ (ORCPT ); Tue, 24 Aug 2021 11:33:25 -0400 Received: from gate.crashing.org ([63.228.1.57]:35656 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238217AbhHXPdY (ORCPT ); Tue, 24 Aug 2021 11:33:24 -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 17OFSFBJ017344; Tue, 24 Aug 2021 10:28:15 -0500 Received: (from segher@localhost) by gate.crashing.org (8.14.1/8.14.1/Submit) id 17OFSEsh017341; Tue, 24 Aug 2021 10:28:14 -0500 X-Authentication-Warning: gate.crashing.org: segher set sender to segher@kernel.crashing.org using -f Date: Tue, 24 Aug 2021 10:28:13 -0500 From: Segher Boessenkool To: Christophe Leroy Cc: Paul Mackerras , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] powerpc/32: Don't use lmw/stmw for saving/restoring non volatile regs Message-ID: <20210824152813.GG1583@gate.crashing.org> References: <316c543b8906712c108985c8463eec09c8db577b.1629732542.git.christophe.leroy@csgroup.eu> <20210823184648.GY1583@gate.crashing.org> <9bbc9797-cfc7-1484-90ad-2146ff1a5e18@csgroup.eu> <20210824131600.GF1583@gate.crashing.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210824131600.GF1583@gate.crashing.org> User-Agent: Mutt/1.4.2.3i Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 24, 2021 at 08:16:00AM -0500, Segher Boessenkool wrote: > On Tue, Aug 24, 2021 at 07:54:22AM +0200, Christophe Leroy wrote: > > >On mpccore both lmw and stmw are only N+1 btw. But the serialization > > >might cost another cycle here? > > > > That coherent on MPC8xx, that's only 2 cycles. > > But on the mpc832x which has a e300c2 core, it looks like I have 10 cycles > > difference. Is anything wrong ? > > I don't know that core very well, I'll have a look. So, I don't see any difference between e300c2 and e300c1 (which is 603 basically, for this) that is significant here. The e300c2 has two integer units instead of just one, but it still has only one load/store unit, and I don't see anything else that could matter either. Huh. Segher