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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, 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 D3DBDC1975A for ; Wed, 25 Mar 2020 05:53:43 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 5FBF520714 for ; Wed, 25 Mar 2020 05:53:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="cJGxg9EV" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5FBF520714 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id BBF436B000A; Wed, 25 Mar 2020 01:53:42 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B70756B000C; Wed, 25 Mar 2020 01:53:42 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A87096B000D; Wed, 25 Mar 2020 01:53:42 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0106.hostedemail.com [216.40.44.106]) by kanga.kvack.org (Postfix) with ESMTP id 9261A6B000A for ; Wed, 25 Mar 2020 01:53:42 -0400 (EDT) Received: from smtpin02.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 3436A52C9 for ; Wed, 25 Mar 2020 05:53:42 +0000 (UTC) X-FDA: 76632817884.02.hat04_5a7fc588f6a27 X-HE-Tag: hat04_5a7fc588f6a27 X-Filterd-Recvd-Size: 7243 Received: from us-smtp-delivery-74.mimecast.com (us-smtp-delivery-74.mimecast.com [216.205.24.74]) by imf12.hostedemail.com (Postfix) with ESMTP for ; Wed, 25 Mar 2020 05:53:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1585115621; 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: in-reply-to:in-reply-to:references:references; bh=KTYHVugK6vWwq8zeRLq4u+jYHxge4eUDyuR1229kPv8=; b=cJGxg9EVgjTjEa8S2HRG6CuEw17QJfLw05yV5hOmAOTuug5/RFM9JGiP1iTiSQbRpm83HD YXPpX4j5McwWq2q9Z+O7k0mBK8rsM/ZbCH6KKD6OrxR2eBkiWntk/j9J5Y1GcIN3zr5fYj lip3M9XzKKi3c+vZenPUtO+asSK8dP4= 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-171-wuIoQrabPEGCtYJEamQXuA-1; Wed, 25 Mar 2020 01:53:39 -0400 X-MC-Unique: wuIoQrabPEGCtYJEamQXuA-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 25E05801E66; Wed, 25 Mar 2020 05:53:37 +0000 (UTC) Received: from localhost (ovpn-12-88.pek2.redhat.com [10.72.12.88]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3EEB294B43; Wed, 25 Mar 2020 05:53:33 +0000 (UTC) Date: Wed, 25 Mar 2020 13:53:31 +0800 From: Baoquan He To: David Rientjes Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, iamjoonsoo.kim@lge.com, hannes@cmpxchg.org, mhocko@kernel.org, vbabka@suse.cz Subject: Re: [PATCH 4/5] mm/vmstat.c: move the per-node stats to the front of /proc/zoneinfo Message-ID: <20200325055331.GB9942@MiWiFi-R3L-srv> References: <20200324142229.12028-1-bhe@redhat.com> <20200324142229.12028-5-bhe@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 03/24/20 at 12:25pm, David Rientjes wrote: > On Tue, 24 Mar 2020, Baoquan He wrote: > > > This moving makes the layout of /proc/zoneinfo more sensible. And there > > are 4 zones at most currently, it doesn't need to scroll down much to get > > to the 1st populated zone, even though the 1st populated zone is MOVABLE > > zone. > > > > Doesn't this introduce risk that it will break existing parsers of > /proc/zoneinfo in subtle ways? > > In some cases /proc/zoneinfo is a tricky file to correctly parse because > you have to rely on the existing order in which it is printed to determine > which zone is being described. We need to print zones even with unmanaged > pages, for instance, otherwise userspace may be unaware of which zones are > supported and what order they are in. That's important to be able to > construct the proper string to use when writing vm.lowmem_reserve_ratio. > > I'd prefer not changing the order of /proc/zoneinfo if it can be avoided > just because the risk outweighs the reward that we may break some > initscript parsers. Oh, I may not describe the change and result clearly. This patch doesn't change zone order at all. I only move the per-node stats to the front of each node, the zone order is completely kept the same, still DMA, DMA32, NORMAL, MOVABLE. Before this patch, per-node stats are printed inside the first populated zone of each node. E.g in this node 2 which only has movable zone, the per-node stats is embedded in the last zone. In fact, this per-node stats are made for the whole node, but not for one zone. Node 2, zone DMA pages free 0 min 0 low 0 high 0 spanned 0 present 0 managed 0 protection: (0, 0, 0, 1024, 1024) Node 2, zone DMA32 pages free 0 min 0 low 0 high 0 spanned 0 present 0 managed 0 protection: (0, 0, 0, 1024, 1024) Node 2, zone Normal pages free 0 min 0 low 0 high 0 spanned 0 present 0 managed 0 protection: (0, 0, 0, 8192, 8192) Node 2, zone Movable per-node stats --------------------------->> start of per-node stats nr_inactive_anon 42 nr_active_anon 11787 nr_inactive_file 32222 nr_active_file 6081 nr_unevictable 0 nr_slab_reclaimable 0 nr_slab_unreclaimable 0 ...... --------- (mid items are omitted) nr_anon_transparent_hugepages 0 nr_unstable 0 nr_vmscan_write 0 nr_vmscan_immediate_reclaim 0 nr_dirtied 25523 nr_written 25113 nr_kernel_misc_reclaimable 0 ------------------------->> end of per-node stats pages free 211331 ------------------------->> start printing data of zone Movable min 3524 low 4405 high 5286 spanned 262144 present 262144 managed 262144 protection: (0, 0, 0, 0, 0) nr_free_pages 211331 nr_zone_inactive_anon 42 nr_zone_active_anon 11787 nr_zone_inactive_file 32222 nr_zone_active_file 6081 nr_zone_unevictable 0 nr_zone_write_pending 2 With this patch applied, only the per-node stats part is moved to the front of each node. Node 2, per-node stats --------------------------->> start of per-node stats nr_inactive_anon 42 nr_active_anon 12358 nr_inactive_file 33139 nr_active_file 10088 nr_unevictable 0 nr_slab_reclaimable 0 ...... --------- (mid items are omitted) nr_vmscan_write 0 nr_vmscan_immediate_reclaim 0 nr_dirtied 9082 nr_written 8844 nr_kernel_misc_reclaimable 0 nr_foll_pin_acquired 0 nr_foll_pin_released 0 ------------------------->> end of per-node stats Node 2, zone DMA pages free 0 min 0 low 0 high 0 spanned 0 present 0 managed 0 Node 2, zone DMA32 pages free 0 min 0 low 0 high 0 spanned 0 present 0 managed 0 Node 2, zone Normal pages free 0 min 0 low 0 high 0 spanned 0 present 0 managed 0 Node 2, zone Movable pages free 205601 ------------------------->> start printing data of zone Movable min 3525 low 4406 high 5287 spanned 262144 present 262144 managed 262144 protection: (0, 0, 0, 0) nr_free_pages 205601 nr_zone_inactive_anon 42 nr_zone_active_anon 12358 ........