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=-11.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 196A2C433E0 for ; Thu, 21 Jan 2021 05:31:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BB59223888 for ; Thu, 21 Jan 2021 05:31:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726126AbhAUFbC (ORCPT ); Thu, 21 Jan 2021 00:31:02 -0500 Received: from a1.mail.mailgun.net ([198.61.254.60]:14032 "EHLO a1.mail.mailgun.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725275AbhAUFar (ORCPT ); Thu, 21 Jan 2021 00:30:47 -0500 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1611207008; h=Content-Transfer-Encoding: MIME-Version: Message-Id: Date: Subject: Cc: To: From: Sender; bh=hfAxKpHRFM9Y26tV/QvUdyavnpRphrMju5aLp3NQ+4Y=; b=lZ5qIGYqRgP6urTtbdy3jJrIdj0tEsniLd0HB3forAJJfTrr1OIhp918KxUIp9UY9plEzZmZ bk++7GQGmB9BsgcLahSxCwFJCIdQbNJgnzfFOEVSvEjm9nu+33LcvLX1/lW8mL6pn2HqBHwb 89W8koEx2VjnJJrWLx86csY8pRQ= X-Mailgun-Sending-Ip: 198.61.254.60 X-Mailgun-Sid: WyI0MWYwYSIsICJsaW51eC1rZXJuZWxAdmdlci5rZXJuZWwub3JnIiwgImJlOWU0YSJd Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n07.prod.us-west-2.postgun.com with SMTP id 600911365677aca7bd782bbd (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Thu, 21 Jan 2021 05:29:26 GMT Sender: sudaraja=codeaurora.org@mg.codeaurora.org Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 8D77BC43461; Thu, 21 Jan 2021 05:29:26 +0000 (UTC) Received: from th-lint-014.qualcomm.com (i-global254.qualcomm.com [199.106.103.254]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: sudaraja) by smtp.codeaurora.org (Postfix) with ESMTPSA id 5BDA1C433C6; Thu, 21 Jan 2021 05:29:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 5BDA1C433C6 Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; spf=fail smtp.mailfrom=sudaraja@codeaurora.org From: Sudarshan Rajagopalan To: linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Catalin Marinas , Will Deacon , Anshuman Khandual , David Hildenbrand Cc: Sudarshan Rajagopalan Subject: [PATCH 0/1] arm64/sparsemem: reduce SECTION_SIZE_BITS Date: Wed, 20 Jan 2021 21:29:12 -0800 Message-Id: X-Mailer: git-send-email 2.25.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This patch is the follow-up from the discussions in the thread [1]. Reducing the section size has the merit of reducing wastage of reserved memory for vmmemmap mappings for sections with large memory holes. Also with smaller section size gives more grunularity and agility for memory hot(un)plugging. But there are also constraints in reducing SECTION_SIZE_BIT: - Should accommodate highest order page for a given config - Should not break PMD mapping in vmemmap for 4K pages - Should not consume too many page->flags bits reducing space for other info This patch uses the suggestions from Anshuman Khandual and David Hildenbrand in thread [1] to set the least possible section size to 128MB for 4K and 16K base page size configs for simplicity, and to 512MB for 64K base page size config. [1] https://lore.kernel.org/lkml/cover.1609895500.git.sudaraja@codeaurora.org/T/#m8ee60ae69db5e9eb06ca7999c43828d49ccb9626 Sudarshan Rajagopalan (1): arm64/sparsemem: reduce SECTION_SIZE_BITS arch/arm64/include/asm/sparsemem.h | 23 +++++++++++++++++++++-- 1 file changed, 21 insertions(+), 2 deletions(-) -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project