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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 79BE2C04A95 for ; Sun, 25 Sep 2022 17:51:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231256AbiIYRvZ (ORCPT ); Sun, 25 Sep 2022 13:51:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46544 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230411AbiIYRvY (ORCPT ); Sun, 25 Sep 2022 13:51:24 -0400 Received: from mout.gmx.net (mout.gmx.net [212.227.17.22]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4C7FD1EEFA for ; Sun, 25 Sep 2022 10:51:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1664128274; bh=Lnp3MRasoMYtdyT+aT4STQA4Hg1xnGyW+HGdsB5lhXM=; h=X-UI-Sender-Class:Date:Subject:To:References:From:In-Reply-To; b=bnJS+/81kz8SnJp+Xcrw7ksTlKHU+vUYOhXpbG4QbROX9Q3rxj41mkmIla+Ghh9Cw 7J/TDi06vhQOSubLstWNI0r2lCrjlASTZ98z8ylzpWkyURkCHJChG+WO2tbNUnHd3z 8DlRRbLQthj+AVftcaoAmRrPLmrST2tB9pCM3FEI= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c Received: from [192.168.20.60] ([92.116.188.118]) by mail.gmx.net (mrgmx104 [212.227.17.168]) with ESMTPSA (Nemesis) id 1MqJqN-1ozDUH0ziN-00nMWs; Sun, 25 Sep 2022 19:51:14 +0200 Message-ID: <92a8b235-7d04-9931-a153-440adbc8802a@gmx.de> Date: Sun, 25 Sep 2022 19:51:11 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.3.0 Subject: Re: [PATCH][RFC] parisc: Use local tlb purges only on UP machines Content-Language: en-US To: John David Anglin , linux-parisc@vger.kernel.org, James Bottomley References: From: Helge Deller In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:PfdYFoa3ATzPJA6lXIUMY7JQ9p2l14SY5kXrQ0fx/f9ikpV7CV0 jQLkmP0JoWVMRg2fkKK+9E5DBpbWel5j/eou0laLmHwICE1nmT/GiHFrgLPg0SP15WUYmVM IO8lakRxOIZrlDnUTfiQp80EishPcl5cOvk1rv9FvBXO2UY1F1H75FEFCcY5750PvNXBg2H rla4YCJqrPdqwreQI1qxg== X-UI-Out-Filterresults: notjunk:1;V03:K0:3MuovWY/pKQ=:eyFcFwP/8pVf6mYMdPdKg0 deEr8nZK3pLuxq70RnhwiSxr+LQd+qF6lg+B60duNiI/5X/bEQi1RlhuBISqAnI3eTAg1OzBW JW36Rr3rWGVonoVakuEzgxVkRk3RnlKOGlHljVvIJS/fBqpFLo7BGhL2Cv+1N/RTMXmn3EFSh uuM/FeyEgDgdonyL7Q7ucdbRH74xn46SR5TmZr+G758tRTShCd7XNbyE/AUJLkJOkS3klx29T e0BJbUQHoBiguUfGL8h4Xv2CQNbOLwbtA+Kd9CSFpVJWBq2bwA9XntHat31jKLjP+Adxc59tc e31Z5EH5sZJ5jaSHCJmwFKtoys97Hc0bSZfHePhg9gp1sfJTTCGnKpGLNQRzhZqsHjuidx4ha O6XbZJHFaqO8Aebi8budVkKvPLjfpFKwJ0R+rRtYfaceGLr3FHyUw1RQx3YBHVm5HYaeblRab 8rwm1n3FG94ELilzT75VWm3Pcq7SfAEiXZIAJ5R0Kaqpwqfhl9GAwoczNeR3V1hgRSxa+Bo/8 09xuLCpUhQEGZFeSOkPwdLI5LtMXV0KvfR/82tbNDAdYW0Nw3yzLdf7gZXK2h5jshXTCKSOWI s0f5WM0dT1k6VvguJRPQXG3Unw+iDHd0qmBH43Tey2KbR3p4p0lsGHksXcJGnEwLIJmHcSFOG UB9CpB3THJMM1j7bnmsUUJpWF+pCx1n01jULom/aO216d1gwfpOrXfOTwxzh+VEAMZLb+9U8H 0A0ANwYFsSS5hMTvvT6QHlpgo3IQE70+tb/k/xKGI9xx0CQ1DDDKV4ofgh4sxxBVdpPgfuU+K bFjgPM7uJYzy+jIGyIYBC594eOXT+zLv6HSnaZlR34OmOkesINhecJabvA3GbaorLPP8brFto eqh6lIK65X8/61vtszSA77bsENoSE7qHi0ujkPMmCjkhJvn+ld24aJpA80R8g4/eDESj3lB54 7mK7uyFAWLzxnO9bYd9jfMpKE3CBIQqDkNMj4mdtQz4kFaPm6rSL0Mdu5hXkiRKTuj7/GbwM4 YR1K3Oa684bhPELAyToIiTh4CWtkaDnr6Jr/o0v5AouXx6RDCugDQ9IEnu0OJsHJ/Zd1slOl4 wGCAUNyw93V/PW6zH8rhkRBwIlKPeN8SvrlAT4r9Onb2zTbrDRqKxm/nbz3KLfbfTbvbdK2RA z5ozd3eNq8SVRGFiQ0GNzW5b18 Precedence: bulk List-ID: X-Mailing-List: linux-parisc@vger.kernel.org On 9/25/22 16:33, John David Anglin wrote: > I believe this change is wrong and will reduce performance. Yes, could be. That's why intentionally marked it RFC. > The TLB setup for a TMPALIAS flush is local to any given CPU. So, we > should only need a local TLB purge. Can those function theoretially be preempted? If so, could it be scheduled on another CPU where the TMPALIAS isn't flush= ed? > A local TLB purge doesn't require locking to serialize PxTLB broadcasts.= =C2=A0 It is also=C2=A0 faster than > a global TLB purges True. > Indeed, the case that might be wrong is the one that uses pdtlb. Which do you have in mind here? > It potentially needs serialization > on SMP machines.=C2=A0 See comment in pgtable.h. One goal of that patch was to drop the CONFIG_PA20 ifdef case, because a 32-bit kernel could be compiled for PA8000 in which case the "pdtlb,l" will burn the machine. I'll send another patch which takes care of this without changing the local purges of pdtlb on 64bit CPUs. Helge