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=-17.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 9A981C433FE for ; Mon, 7 Dec 2020 12:49:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 40D1B23403 for ; Mon, 7 Dec 2020 12:49:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725879AbgLGMtJ (ORCPT ); Mon, 7 Dec 2020 07:49:09 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:30238 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725800AbgLGMtJ (ORCPT ); Mon, 7 Dec 2020 07:49:09 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1607345262; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Gj9yTnv0pMQFcNLl2DqcFbB30RkjtniH8pQgiWQVvag=; b=IaeCR2sJifCHM2pujPmFWEz6EpeBPm7k9VNo9UvcSTI9MwLj3n0diBsYBX/QV72prI3D7K HoVF6w+vMxa1tbx4zuTxqLJW/OxKS/2SBCyW3KGnzUFimNB+funPB8krThmXHopVXh9GAZ OXl2/QQLV7nZxkJ5MWL+e+k0LKsEB7M= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-32--5iskghnOymQqZzHpw-H-w-1; Mon, 07 Dec 2020 07:47:38 -0500 X-MC-Unique: -5iskghnOymQqZzHpw-H-w-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 646D9800D55; Mon, 7 Dec 2020 12:47:34 +0000 (UTC) Received: from [10.36.114.33] (ovpn-114-33.ams2.redhat.com [10.36.114.33]) by smtp.corp.redhat.com (Postfix) with ESMTP id 357EB5D9DE; Mon, 7 Dec 2020 12:47:27 +0000 (UTC) Subject: Re: [External] Re: [PATCH v7 03/15] mm/hugetlb: Introduce a new config HUGETLB_PAGE_FREE_VMEMMAP To: Muchun Song Cc: Jonathan Corbet , Mike Kravetz , Thomas Gleixner , mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, dave.hansen@linux.intel.com, luto@kernel.org, Peter Zijlstra , viro@zeniv.linux.org.uk, Andrew Morton , paulmck@kernel.org, mchehab+huawei@kernel.org, pawan.kumar.gupta@linux.intel.com, Randy Dunlap , oneukum@suse.com, anshuman.khandual@arm.com, jroedel@suse.de, Mina Almasry , David Rientjes , Matthew Wilcox , Oscar Salvador , Michal Hocko , "Song Bao Hua (Barry Song)" , Xiongchun duan , linux-doc@vger.kernel.org, LKML , Linux Memory Management List , linux-fsdevel References: <20201130151838.11208-1-songmuchun@bytedance.com> <20201130151838.11208-4-songmuchun@bytedance.com> <2ec1d360-c8c8-eb7b-2afe-b75ee61cfcea@redhat.com> From: David Hildenbrand Organization: Red Hat GmbH Message-ID: Date: Mon, 7 Dec 2020 13:47:26 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On 07.12.20 13:42, Muchun Song wrote: > On Mon, Dec 7, 2020 at 8:19 PM David Hildenbrand wrote: >> >> On 30.11.20 16:18, Muchun Song wrote: >>> The purpose of introducing HUGETLB_PAGE_FREE_VMEMMAP is to configure >>> whether to enable the feature of freeing unused vmemmap associated >>> with HugeTLB pages. And this is just for dependency check. Now only >>> support x86. >> >> x86 - i386 and x86-64? (I assume the latter only ;) ) > > Yeah, you are right. Only the latter support SPARSEMEM_VMEMMAP. > >> >>> >>> Signed-off-by: Muchun Song >>> --- >>> arch/x86/mm/init_64.c | 2 +- >>> fs/Kconfig | 14 ++++++++++++++ >>> 2 files changed, 15 insertions(+), 1 deletion(-) >>> >>> diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c >>> index 0a45f062826e..0435bee2e172 100644 >>> --- a/arch/x86/mm/init_64.c >>> +++ b/arch/x86/mm/init_64.c >>> @@ -1225,7 +1225,7 @@ static struct kcore_list kcore_vsyscall; >>> >>> static void __init register_page_bootmem_info(void) >>> { >>> -#ifdef CONFIG_NUMA >>> +#if defined(CONFIG_NUMA) || defined(CONFIG_HUGETLB_PAGE_FREE_VMEMMAP) >>> int i; >>> >> >> Why does this hunk belong into this patch? Looks like this should go >> into another patch. > > Of course can. But Mike suggests that it is better to use it when > introducing a new config. Because this config depends on > HAVE_BOOTMEM_INFO_NODE. And register_page_bootmem_info > is aimed to register bootmem info. So maybe it is reasonable from > this point of view. What is your opinion? > Ah, I see. Maybe mention in the patch description, because the "Introduce a new config HUGETLB_PAGE_FREE_VMEMMAP" part left me clueless. Stumbling over this change only left me rather clueless. >> >>> for_each_online_node(i) >>> diff --git a/fs/Kconfig b/fs/Kconfig >>> index 976e8b9033c4..4961dd488444 100644 >>> --- a/fs/Kconfig >>> +++ b/fs/Kconfig >>> @@ -245,6 +245,20 @@ config HUGETLBFS >>> config HUGETLB_PAGE >>> def_bool HUGETLBFS >>> >>> +config HUGETLB_PAGE_FREE_VMEMMAP >>> + def_bool HUGETLB_PAGE >>> + depends on X86 >>> + depends on SPARSEMEM_VMEMMAP >>> + depends on HAVE_BOOTMEM_INFO_NODE >>> + help >>> + When using HUGETLB_PAGE_FREE_VMEMMAP, the system can save up some >>> + memory from pre-allocated HugeTLB pages when they are not used. >>> + 6 pages per 2MB HugeTLB page and 4094 per 1GB HugeTLB page. >> >> Calculations only apply to 4k base pages, no? > > No, if the base page is not 4k, we also can free 6 pages. > > For example: > > If the base page size is 64k, the PMD huge page size is 512MB. We also Note that 2MB huge pages on arm64 with 64k base pages are possible as well. Also, I think powerpc always has 16MB huge pages, independent of base page sizes. -- Thanks, David / dhildenb