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 06212FA373D for ; Mon, 24 Oct 2022 07:33:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229729AbiJXHdR (ORCPT ); Mon, 24 Oct 2022 03:33:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38460 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229716AbiJXHdO (ORCPT ); Mon, 24 Oct 2022 03:33:14 -0400 Received: from out2-smtp.messagingengine.com (out2-smtp.messagingengine.com [66.111.4.26]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BF980606A9; Mon, 24 Oct 2022 00:33:12 -0700 (PDT) Received: from compute3.internal (compute3.nyi.internal [10.202.2.43]) by mailout.nyi.internal (Postfix) with ESMTP id 1A1AC5C00CC; Mon, 24 Oct 2022 03:33:12 -0400 (EDT) Received: from imap51 ([10.202.2.101]) by compute3.internal (MEProxy); Mon, 24 Oct 2022 03:33:12 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=arndb.de; h=cc :cc:content-type:date:date:from:from:in-reply-to:in-reply-to :message-id:mime-version:references:reply-to:sender:subject :subject:to:to; s=fm2; t=1666596792; x=1666683192; bh=MLgwl6qVQ1 d5bswGgDHxIEJUCPcVEho8D9vRKEmhmk8=; b=GHgwqBJ1of6xGRv2pG2BGEt8rE CewjyOnqG3XsUJOJdIk9/EbkQKJtPGc71OXxQ4Z85kQPLrrlOL0rB4lnZl8HLVjy sL64F831eIsoYiZOo9PjdNOjd/BjBYFBj0PwZ+n2IZJFws6958OvauvdcTUbj6Xb YAr94iVFFIJYpN29b+cbjGpjOzma0LABf7WPmoe6PS7PhnXuRNopy5RMTG593Hgg gC+TxNaBT5kVJmUi4kU685zxWc3+UhLrKi4h4866RCchEH0Z1ZbwAMPl9AvZHg4T IbIzj1S+xFoxWGl1Qx84pJSZC4X7ZgG1vE97hMqp9xPwuDUPFO/cqI1jZSHA== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-type:date:date:feedback-id :feedback-id:from:from:in-reply-to:in-reply-to:message-id :mime-version:references:reply-to:sender:subject:subject:to:to :x-me-proxy:x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s= fm3; t=1666596792; x=1666683192; bh=MLgwl6qVQ1d5bswGgDHxIEJUCPcV Eho8D9vRKEmhmk8=; b=aESBKGu4MQ+NP6k7XUxbGLXgLZBIv/NbQmZz+8PUdEom ILy9GBFMOeowzyFjolQsKijHfCfiVos8c0zu+vkmwlQWvTcDdD6BFEhIp/2U1Yos bIAJH+c5iJIVrIkfMwKXqKyjouaiKQW3I0qJq3FfWw0SpunlPNXb6qvLGyyr9wwE d/kpCfcJNwKUY3aqbNLYQS/8BfdYoC3sUo6yZRhq8GH6pCxa0k5z1eXTIgTBLTwW SIGHrfH57n/mXNmD2rMjKfviyRsXWh9aCSbhFoovg0BxFrWNcctSNq/zlL2dztRW s6jgP5GqVavI7irhlwP5PZ7WRz8bRvFoFhIwhe8xZw== X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvfedrgedtfedguddvfecutefuodetggdotefrod ftvfcurfhrohhfihhlvgemucfhrghsthforghilhdpqfgfvfdpuffrtefokffrpgfnqfgh necuuegrihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmd enucfjughrpefofgggkfgjfhffhffvvefutgesthdtredtreertdenucfhrhhomhepfdet rhhnugcuuegvrhhgmhgrnhhnfdcuoegrrhhnugesrghrnhgusgdruggvqeenucggtffrrg htthgvrhhnpeeivdeutdetiefgffdvteehtdegkeehvdelueetheeggeelkedutdfggeeg vedtheenucffohhmrghinheprhgvrggtthhoshdrohhrghenucevlhhushhtvghrufhiii gvpedtnecurfgrrhgrmhepmhgrihhlfhhrohhmpegrrhhnugesrghrnhgusgdruggv X-ME-Proxy: Feedback-ID: i56a14606:Fastmail Received: by mailuser.nyi.internal (Postfix, from userid 501) id 89108B60086; Mon, 24 Oct 2022 03:33:09 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface User-Agent: Cyrus-JMAP/3.7.0-alpha0-1047-g9e4af4ada4-fm-20221005.001-g9e4af4ad Mime-Version: 1.0 Message-Id: In-Reply-To: References: <20220815071332.627393-1-yuzhao@google.com> <20220815071332.627393-9-yuzhao@google.com> Date: Mon, 24 Oct 2022 09:30:09 +0200 From: "Arnd Bergmann" To: "Linus Torvalds" , "Maciej W. Rozycki" Cc: "Matthew Wilcox" , "Peter Zijlstra" , "the arch/x86 maintainers" , "Yu Zhao" , "Andrew Morton" , "Andi Kleen" , "Aneesh Kumar" , "Catalin Marinas" , "Dave Hansen" , "Hillf Danton" , "Jens Axboe" , "Johannes Weiner" , "Jonathan Corbet" , "Mel Gorman" , "Michael Larabel" , "Michal Hocko" , "Mike Rapoport" , "Tejun Heo" , "Vlastimil Babka" , "Will Deacon" , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, page-reclaim@google.com, "Brian Geffon" , "Jan Alexander Steffens" , "Oleksandr Natalenko" , "Steven Barrett" , "Suleiman Souhlal" , "Daniel Byrne" , "Donald Carr" , =?UTF-8?Q?Holger_Hoffst=C3=A4tte?= , "Konstantin Kharlamov" , "Shuang Zhai" , "Sofia Trinh" , "Vaibhav Jain" Subject: Re: [PATCH v14 08/14] mm: multi-gen LRU: support page table walks Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Oct 23, 2022, at 20:35, Linus Torvalds wrote: > > Honestly, I wouldn't mind upgrading the minimum requirements to at > least M586TSC - leaving some of those early "fake Pentium" clones > behind too. Because 'rdtsc' is probably an even worse issue than > CMPXCHG8B. Kconfig treats X86_CMPXCHG64 as a strict subset of X86_TSC (except when enabling X86_PAE, which relies on cx8), so requiring both sounds like a good idea. >From the Kconfig history, I see you initially only enabled cx8 unconditionally for a couple of CPUs in 982d007a6eec ("x86: Optimize cmpxchg64() at build-time some more"), and Matthew Whitehead extended that list in f960cfd12650 ("x86/Kconfig: Add missing i586-class CPUs to the X86_CMPXCHG64 Kconfig group"). There are still a handful of CPUs that according to [1] claim cx8 support that we leave disabled, specifically the Kconfig symbols for MWINCHIP3D, MCRUSOE, MEFFICEON, MCYRIXIII, MVIAC3_2 and MVIAC7 should have both tsc and cx8, while the older MWINCHIPC6 and a small subset of M586 (Cyrix 6x86mx, C-II and AMD K5) apparently have cx8 but not tsc. Would you drop support for the 686-class chips that currently don't use cmpxchg8b, or just remove CONFIG_X86_CMPXCHG64 and assume they work after all? Arnd [1] https://reactos.org/wiki/Supported_Hardware/CPU 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 72ADEC3A59D for ; Mon, 24 Oct 2022 07:34:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:Subject:Cc:To:From:Date:References: In-Reply-To:Message-Id:Mime-Version:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=bS+9jzoBo4G7oUg3++Rm4BTa9nQkO0Vc3ESvdaQBkrA=; b=cixkvfAYSdU/NJ b73KzjBmen+Bev7GZeji/7IgLQ1WtQBHfqS7HpOxhlYJHuI38OxA0/49ujx13lHQXBfs3F/QsHx/T wVcjx4oF0WawAYqLjskrz50op2e5Wacz+DNAa4XUIpLFrRdSz/hz8XUFHZBxTMpFGplbLQUE/BCRl iO8xf7Lob5Q5UYsiH1T7vIzpnckXihDst6CSUm/iJu+rgcNc4zzuBlDHNKsOPJOGeoFQZfGo9xHNU GBWsZask7cZjSkd7TdQ7l+Q3cYwrTs8o6p0jjRXrFvosTFBAbZzF11RGDbpDECtM9AkZUcin8kBvS j0B/xs2oAc22rg0K8W7Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1omrxY-00HUkQ-Mu; Mon, 24 Oct 2022 07:33:20 +0000 Received: from out2-smtp.messagingengine.com ([66.111.4.26]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1omrxW-00HUhT-1M for linux-arm-kernel@lists.infradead.org; Mon, 24 Oct 2022 07:33:19 +0000 Received: from compute3.internal (compute3.nyi.internal [10.202.2.43]) by mailout.nyi.internal (Postfix) with ESMTP id 1A1AC5C00CC; Mon, 24 Oct 2022 03:33:12 -0400 (EDT) Received: from imap51 ([10.202.2.101]) by compute3.internal (MEProxy); Mon, 24 Oct 2022 03:33:12 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=arndb.de; h=cc :cc:content-type:date:date:from:from:in-reply-to:in-reply-to :message-id:mime-version:references:reply-to:sender:subject :subject:to:to; s=fm2; t=1666596792; x=1666683192; bh=MLgwl6qVQ1 d5bswGgDHxIEJUCPcVEho8D9vRKEmhmk8=; b=GHgwqBJ1of6xGRv2pG2BGEt8rE CewjyOnqG3XsUJOJdIk9/EbkQKJtPGc71OXxQ4Z85kQPLrrlOL0rB4lnZl8HLVjy sL64F831eIsoYiZOo9PjdNOjd/BjBYFBj0PwZ+n2IZJFws6958OvauvdcTUbj6Xb YAr94iVFFIJYpN29b+cbjGpjOzma0LABf7WPmoe6PS7PhnXuRNopy5RMTG593Hgg gC+TxNaBT5kVJmUi4kU685zxWc3+UhLrKi4h4866RCchEH0Z1ZbwAMPl9AvZHg4T IbIzj1S+xFoxWGl1Qx84pJSZC4X7ZgG1vE97hMqp9xPwuDUPFO/cqI1jZSHA== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-type:date:date:feedback-id :feedback-id:from:from:in-reply-to:in-reply-to:message-id :mime-version:references:reply-to:sender:subject:subject:to:to :x-me-proxy:x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s= fm3; t=1666596792; x=1666683192; bh=MLgwl6qVQ1d5bswGgDHxIEJUCPcV Eho8D9vRKEmhmk8=; b=aESBKGu4MQ+NP6k7XUxbGLXgLZBIv/NbQmZz+8PUdEom ILy9GBFMOeowzyFjolQsKijHfCfiVos8c0zu+vkmwlQWvTcDdD6BFEhIp/2U1Yos bIAJH+c5iJIVrIkfMwKXqKyjouaiKQW3I0qJq3FfWw0SpunlPNXb6qvLGyyr9wwE d/kpCfcJNwKUY3aqbNLYQS/8BfdYoC3sUo6yZRhq8GH6pCxa0k5z1eXTIgTBLTwW SIGHrfH57n/mXNmD2rMjKfviyRsXWh9aCSbhFoovg0BxFrWNcctSNq/zlL2dztRW s6jgP5GqVavI7irhlwP5PZ7WRz8bRvFoFhIwhe8xZw== X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvfedrgedtfedguddvfecutefuodetggdotefrod ftvfcurfhrohhfihhlvgemucfhrghsthforghilhdpqfgfvfdpuffrtefokffrpgfnqfgh necuuegrihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmd enucfjughrpefofgggkfgjfhffhffvvefutgesthdtredtreertdenucfhrhhomhepfdet rhhnugcuuegvrhhgmhgrnhhnfdcuoegrrhhnugesrghrnhgusgdruggvqeenucggtffrrg htthgvrhhnpeeivdeutdetiefgffdvteehtdegkeehvdelueetheeggeelkedutdfggeeg vedtheenucffohhmrghinheprhgvrggtthhoshdrohhrghenucevlhhushhtvghrufhiii gvpedtnecurfgrrhgrmhepmhgrihhlfhhrohhmpegrrhhnugesrghrnhgusgdruggv X-ME-Proxy: Feedback-ID: i56a14606:Fastmail Received: by mailuser.nyi.internal (Postfix, from userid 501) id 89108B60086; Mon, 24 Oct 2022 03:33:09 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface User-Agent: Cyrus-JMAP/3.7.0-alpha0-1047-g9e4af4ada4-fm-20221005.001-g9e4af4ad Mime-Version: 1.0 Message-Id: In-Reply-To: References: <20220815071332.627393-1-yuzhao@google.com> <20220815071332.627393-9-yuzhao@google.com> Date: Mon, 24 Oct 2022 09:30:09 +0200 From: "Arnd Bergmann" To: "Linus Torvalds" , "Maciej W. Rozycki" Cc: "Matthew Wilcox" , "Peter Zijlstra" , "the arch/x86 maintainers" , "Yu Zhao" , "Andrew Morton" , "Andi Kleen" , "Aneesh Kumar" , "Catalin Marinas" , "Dave Hansen" , "Hillf Danton" , "Jens Axboe" , "Johannes Weiner" , "Jonathan Corbet" , "Mel Gorman" , "Michael Larabel" , "Michal Hocko" , "Mike Rapoport" , "Tejun Heo" , "Vlastimil Babka" , "Will Deacon" , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, page-reclaim@google.com, "Brian Geffon" , "Jan Alexander Steffens" , "Oleksandr Natalenko" , "Steven Barrett" , "Suleiman Souhlal" , "Daniel Byrne" , "Donald Carr" , =?UTF-8?Q?Holger_Hoffst=C3=A4tte?= , "Konstantin Kharlamov" , "Shuang Zhai" , "Sofia Trinh" , "Vaibhav Jain" Subject: Re: [PATCH v14 08/14] mm: multi-gen LRU: support page table walks X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221024_003318_185257_A1EC487E X-CRM114-Status: UNSURE ( 9.35 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Sun, Oct 23, 2022, at 20:35, Linus Torvalds wrote: > > Honestly, I wouldn't mind upgrading the minimum requirements to at > least M586TSC - leaving some of those early "fake Pentium" clones > behind too. Because 'rdtsc' is probably an even worse issue than > CMPXCHG8B. Kconfig treats X86_CMPXCHG64 as a strict subset of X86_TSC (except when enabling X86_PAE, which relies on cx8), so requiring both sounds like a good idea. >From the Kconfig history, I see you initially only enabled cx8 unconditionally for a couple of CPUs in 982d007a6eec ("x86: Optimize cmpxchg64() at build-time some more"), and Matthew Whitehead extended that list in f960cfd12650 ("x86/Kconfig: Add missing i586-class CPUs to the X86_CMPXCHG64 Kconfig group"). There are still a handful of CPUs that according to [1] claim cx8 support that we leave disabled, specifically the Kconfig symbols for MWINCHIP3D, MCRUSOE, MEFFICEON, MCYRIXIII, MVIAC3_2 and MVIAC7 should have both tsc and cx8, while the older MWINCHIPC6 and a small subset of M586 (Cyrix 6x86mx, C-II and AMD K5) apparently have cx8 but not tsc. Would you drop support for the 686-class chips that currently don't use cmpxchg8b, or just remove CONFIG_X86_CMPXCHG64 and assume they work after all? Arnd [1] https://reactos.org/wiki/Supported_Hardware/CPU _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel