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=-2.2 required=3.0 tests=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 493B0C33CB3 for ; Sat, 1 Feb 2020 14:07:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 26A842051A for ; Sat, 1 Feb 2020 14:07:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726718AbgBAOHI (ORCPT ); Sat, 1 Feb 2020 09:07:08 -0500 Received: from gate.crashing.org ([63.228.1.57]:47802 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726505AbgBAOHI (ORCPT ); Sat, 1 Feb 2020 09:07:08 -0500 Received: from gate.crashing.org (localhost.localdomain [127.0.0.1]) by gate.crashing.org (8.14.1/8.14.1) with ESMTP id 011E6WZ9013963; Sat, 1 Feb 2020 08:06:32 -0600 Received: (from segher@localhost) by gate.crashing.org (8.14.1/8.14.1/Submit) id 011E6TK9013962; Sat, 1 Feb 2020 08:06:29 -0600 X-Authentication-Warning: gate.crashing.org: segher set sender to segher@kernel.crashing.org using -f Date: Sat, 1 Feb 2020 08:06:29 -0600 From: Segher Boessenkool To: Christophe Leroy Cc: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] powerpc/32s: Don't flush all TLBs when flushing one page Message-ID: <20200201140629.GM22482@gate.crashing.org> References: <20200131155150.GD22482@gate.crashing.org> <27cef66b-df5b-0baa-abac-5532e58bd055@c-s.fr> <20200131193833.GF22482@gate.crashing.org> <248a3cf3-1b5e-a6e1-ceec-0e3904d1cf51@c-s.fr> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <248a3cf3-1b5e-a6e1-ceec-0e3904d1cf51@c-s.fr> 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 Sat, Feb 01, 2020 at 08:27:03AM +0100, Christophe Leroy wrote: > Le 31/01/2020 à 20:38, Segher Boessenkool a écrit : > >On Fri, Jan 31, 2020 at 05:15:20PM +0100, Christophe Leroy wrote: > >>Le 31/01/2020 à 16:51, Segher Boessenkool a écrit : > >>>On Fri, Jan 31, 2020 at 03:37:34PM +0000, Christophe Leroy wrote: > >>>>When the range is a single page, do a page flush instead. > >>> > >>>>+ start &= PAGE_MASK; > >>>>+ end = (end - 1) | ~PAGE_MASK; > >>>> if (!Hash) { > >>>>- _tlbia(); > >>>>+ if (end - start == PAGE_SIZE) > >>>>+ _tlbie(start); > >>>>+ else > >>>>+ _tlbia(); > >>>> return; > >>>> } > >>> > >>>For just one page, you get end - start == 0 actually? > >> > >>Oops, good catch. > >> > >>Indeed you don't get PAGE_SIZE but (PAGE_SIZE - 1) for just one page. > > > >You have all low bits masked off in both start and end, so you get zero. > >You could make the condion read "if (start == end)? > > No, in end the low bits are set, that's a BIT OR with ~PAGE_MASK, so it > sets all low bits to 1. Oh, wow, yes, I cannot read apparently. Maybe there are some ROUND_DOWN and ROUND_UP macros you could use? Segher