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=-5.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 2C4F0C433E0 for ; Thu, 21 Jan 2021 10:09:57 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id B143B221F0 for ; Thu, 21 Jan 2021 10:09:56 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B143B221F0 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:References:Message-ID:In-Reply-To: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=Yx5J/qOm+kGLRXNx6QnuxE6kQKjG687lz6CmcknXk4A=; b=d/Ih1CCcWUvfj9Hrv0dvx3yjM +wDamoPGqlwT6nOIDsV5ZI6rTXFXu6x7nvNcxFRm1FAg2T5/KMqJf00J+wdGP/2f9G0DpRvekfam3 Dz09OFMVaVH5R3eqVigSFUmmHzfVT0L2q9awV++0tMjuWMO0UdzgQFDX4tDYsNwjjosm8C6XlTCo5 XE9iAIGyeqNOwAc+1rwSiXGSUyWEAMxV8d43EI1+NN5ITlftpxFsW0wCmE8l8ka+kSqpo808PM9aS cgxVcbdTuryJ/WNznqEzvWZKOCHJu0ER9LHmn9nvhJMPTUW+2YVY1u0l+HN1C7lU9dPfUNVhlAG1y c529zjRYQ==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1l2Wt8-0001od-Jn; Thu, 21 Jan 2021 10:08:26 +0000 Received: from gentwo.org ([3.19.106.255]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1l2Wt4-0001ng-P5 for linux-arm-kernel@lists.infradead.org; Thu, 21 Jan 2021 10:08:24 +0000 Received: by gentwo.org (Postfix, from userid 1002) id A245C3F04E; Thu, 21 Jan 2021 10:08:17 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by gentwo.org (Postfix) with ESMTP id A030D3EFF6; Thu, 21 Jan 2021 10:08:17 +0000 (UTC) Date: Thu, 21 Jan 2021 10:08:17 +0000 (UTC) From: Christoph Lameter X-X-Sender: cl@www.lameter.com To: Sudarshan Rajagopalan Subject: Re: [PATCH 1/1] arm64/sparsemem: reduce SECTION_SIZE_BITS In-Reply-To: <43843c5e092bfe3ec4c41e3c8c78a7ee35b69bb0.1611206601.git.sudaraja@codeaurora.org> Message-ID: References: <43843c5e092bfe3ec4c41e3c8c78a7ee35b69bb0.1611206601.git.sudaraja@codeaurora.org> User-Agent: Alpine 2.22 (DEB 394 2020-01-19) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210121_050822_836945_01546FFE X-CRM114-Status: UNSURE ( 9.67 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Anshuman Khandual , Catalin Marinas , David Hildenbrand , linux-kernel@vger.kernel.org, Mike Rapoport , Suren Baghdasaryan , linux-mm@kvack.org, Logan Gunthorpe , Andrew Morton , Steven Price , Will Deacon , linux-arm-kernel@lists.infradead.org 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 Wed, 20 Jan 2021, Sudarshan Rajagopalan wrote: > But there are other problems in reducing SECTION_SIZE_BIT. Reducing it by too > much would over populate /sys/devices/system/memory/ and also consume too many > page->flags bits in the !vmemmap case. Also section size needs to be multiple > of 128MB to have PMD based vmemmap mapping with CONFIG_ARM64_4K_PAGES. There is also the issue of requiring more space in the TLB cache with smaller page sizes. Or does ARM resolve these into smaller TLB entries anyways (going on my x86 kwon how here)? Anyways if there are only a few TLB entries then the effect could be significant. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel