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=-5.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,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 63306C433ED for ; Thu, 6 May 2021 19:15:24 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (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 A38AE6113E for ; Thu, 6 May 2021 19:15:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A38AE6113E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4Fbjvt09Nnz3bTn for ; Fri, 7 May 2021 05:15:22 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=PLRvuvKS; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=PLRvuvKS; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=redhat.com (client-ip=216.205.24.124; helo=us-smtp-delivery-124.mimecast.com; envelope-from=david@redhat.com; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=PLRvuvKS; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=PLRvuvKS; dkim-atps=neutral Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4FbjvG2lqZz2y86 for ; Fri, 7 May 2021 05:14:49 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1620328487; 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=LxJCtrJc+hn1vhOwMRBMiLEsVjLTk4AmYnUbr3bQtaE=; b=PLRvuvKSFI1DBA41oyQZfmh5KBtNY7jp9bfmvhGxSvQHtx0HkfmIdlhEHoaBBb18LF3AOM 6lYi62N3cIRS2MC9cNkAYTtSyTqaEZyJ7/MvGXFS7pLcnBjmicQBouSbd0WuWOO8CFt0Dm U/iwtdnTNMQIyW096DYgRPjOV5+xK6M= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1620328487; 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=LxJCtrJc+hn1vhOwMRBMiLEsVjLTk4AmYnUbr3bQtaE=; b=PLRvuvKSFI1DBA41oyQZfmh5KBtNY7jp9bfmvhGxSvQHtx0HkfmIdlhEHoaBBb18LF3AOM 6lYi62N3cIRS2MC9cNkAYTtSyTqaEZyJ7/MvGXFS7pLcnBjmicQBouSbd0WuWOO8CFt0Dm U/iwtdnTNMQIyW096DYgRPjOV5+xK6M= Received: from mail-ej1-f69.google.com (mail-ej1-f69.google.com [209.85.218.69]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-361-8t-kuzskP1K3In9mbRgPTw-1; Thu, 06 May 2021 15:14:45 -0400 X-MC-Unique: 8t-kuzskP1K3In9mbRgPTw-1 Received: by mail-ej1-f69.google.com with SMTP id z6-20020a17090665c6b02903700252d1ccso2103241ejn.10 for ; Thu, 06 May 2021 12:14:45 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:to:cc:references:from:organization:subject :message-id:date:user-agent:mime-version:in-reply-to :content-language:content-transfer-encoding; bh=LxJCtrJc+hn1vhOwMRBMiLEsVjLTk4AmYnUbr3bQtaE=; b=jH8b98yLA79njbZplUfePNs21qqrxE0OWwEs5WX1YBHMjZrPbD7gNdC1ibS3fNa5n6 MCVvEgqJp4dzrmgF2br4vDMMI00/mlYVsV1nIVuCUNOmNrLqRoOU+7UeNjvHXqB5h5GZ 2FHHpZXG4Sqjp8aSzX0qU1XNN4dPlCFzgWUGPFZyiqhjRr5i7ruIwFQb0Ke1LR5To8Ov ZZ/z8TNvHRoHI5wr63L4urmGi6OltmJKAOgnY24JTmAV2UDDiLYL9jIuHAFCwWn58pD0 cfqNePm+7gi3zBi79dUvtE+65Md6gOEcAq3G8rMb4uqHozVybCkNkWRm0ZukXDTvi3xF gyaA== X-Gm-Message-State: AOAM531L5HY51DImPYVou9pgWg/QbniIT7xCRHh0ZnEhV+qlf5Cc8kUr c0C9nas56IKrnzju3ivPpNHm38i8n1Z0vejXFEZ9HH1ZQVvhfeqJ7svsDu6vgMegEsErD78iHH1 0dK2zRmva/CuKUzwj5c4p+4i4pA== X-Received: by 2002:aa7:d843:: with SMTP id f3mr7130707eds.270.1620328484581; Thu, 06 May 2021 12:14:44 -0700 (PDT) X-Google-Smtp-Source: ABdhPJyMDfCDANHagwyvMGFrV1L6sL7t6UDHQRxiwpmWElp0FfWEi44uao+v+GyT+Pf6/v6QHjNNZw== X-Received: by 2002:aa7:d843:: with SMTP id f3mr7130678eds.270.1620328484331; Thu, 06 May 2021 12:14:44 -0700 (PDT) Received: from [192.168.3.132] (p5b0c64ae.dip0.t-ipconnect.de. [91.12.100.174]) by smtp.gmail.com with ESMTPSA id x7sm1924071ejc.116.2021.05.06.12.14.43 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 06 May 2021 12:14:44 -0700 (PDT) To: Zi Yan References: <20210506152623.178731-1-zi.yan@sent.com> <20210506152623.178731-2-zi.yan@sent.com> <06dfaf69-1173-462c-b85f-8715cb8d108c@redhat.com> <71EE13C0-9CF7-4F1F-9C17-64500A854BD8@nvidia.com> From: David Hildenbrand Organization: Red Hat Subject: Re: [RFC PATCH 1/7] mm: sparse: set/clear subsection bitmap when pages are onlined/offlined. Message-ID: <146a1ec6-38b3-9724-b346-9bb6e7e24c72@redhat.com> Date: Thu, 6 May 2021 21:14:42 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: <71EE13C0-9CF7-4F1F-9C17-64500A854BD8@nvidia.com> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=david@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Michal Hocko , linux-ia64@vger.kernel.org, Wei Yang , Anshuman Khandual , "Rafael J . Wysocki" , x86@kernel.org, Dan Williams , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andy Lutomirski , Thomas Gleixner , linuxppc-dev@lists.ozlabs.org, Andrew Morton , Mike Rapoport , Oscar Salvador Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" >> But glimpsing at patch #2, I'd rather stop right away digging deeper into this series :) > > What is the issue of patch 2, which makes pageblock_order a variable all the time? BTW, patch 2 fixes a bug by exporting pageblock_order, since when HUGETLB_PAGE_SIZE_VARIABLE is set, virtio-mem will not see pageblock_order as a variable, which could happen for PPC_BOOK2S_64 with virtio-men enabled, right? Or is this an invalid combination? virtio_mem is x86_64 only. aarch64 and s390x prototypes are available. If I understood "Make pageblock_order a variable and set it to the max of HUGETLB_PAGE_ORDER, MAX_ORDER - 1" correctly, you're setting the pageblock_order on x86_64 to 4M. That mean's you're no longer grouping for THP but MAX_ORDER - 1, which is not what we want. We want to optimize for THP. Also, that would affect virtio-balloon with free page reporting (report only 4 MiB chunks not 2 MiB chunks). > >> >> I think what would really help is drafting a design of how it all could look like and then first discussing the high-level design, investigating how it could play along with all existing users, existing workloads, and existing use cases. Proposing such changes without a clear picture in mind and a high-level overview might give you some unpleasant reactions from some of the developers around here ;) > > Please see my other email for a high-level design. Also I sent the patchset as a RFC to gather information on users, workloads, use cases I did not know about and I learnt a lot from your replies. :) Feedback is always welcome, but I am not sure why it needs to make people unpleasant. ;) Rather the replies might be unpleasant ;) -- Thanks, David / dhildenb