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=-11.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SIGNED_OFF_BY,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 2BD2FC3279D for ; Tue, 6 Oct 2020 22:11:37 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 430D8208C7 for ; Tue, 6 Oct 2020 22:11:35 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 430D8208C7 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 56D52900002; Tue, 6 Oct 2020 18:11:35 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 51DFE6B005D; Tue, 6 Oct 2020 18:11:35 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 40BB6900002; Tue, 6 Oct 2020 18:11:35 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0133.hostedemail.com [216.40.44.133]) by kanga.kvack.org (Postfix) with ESMTP id 0EDA56B005C for ; Tue, 6 Oct 2020 18:11:35 -0400 (EDT) Received: from smtpin16.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 9F44F824999B for ; Tue, 6 Oct 2020 22:11:34 +0000 (UTC) X-FDA: 77342898108.16.spot43_5405c15271ca Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin16.hostedemail.com (Postfix) with ESMTP id 8B03510134203 for ; Tue, 6 Oct 2020 22:11:34 +0000 (UTC) X-HE-Tag: spot43_5405c15271ca X-Filterd-Recvd-Size: 4143 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf38.hostedemail.com (Postfix) with ESMTP for ; Tue, 6 Oct 2020 22:11:34 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id E07D1B023; Tue, 6 Oct 2020 22:11:32 +0000 (UTC) Subject: Re: [PATCH 3/9] mm, page_alloc: remove setup_pageset() To: Michal Hocko Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Pavel Tatashin , David Hildenbrand , Oscar Salvador , Joonsoo Kim References: <20200922143712.12048-1-vbabka@suse.cz> <20200922143712.12048-4-vbabka@suse.cz> <20201005125946.GY4555@dhcp22.suse.cz> From: Vlastimil Babka Message-ID: <2e6c56aa-a8b0-2d10-eca1-4138424d2db3@suse.cz> Date: Wed, 7 Oct 2020 00:11:32 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <20201005125946.GY4555@dhcp22.suse.cz> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit 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 10/5/20 2:59 PM, Michal Hocko wrote: > On Tue 22-09-20 16:37:06, Vlastimil Babka wrote: >> We initialize boot-time pagesets with setup_pageset(), which sets high and >> batch values that effectively disable pcplists. >> >> We can remove this wrapper if we just set these values for all pagesets in >> pageset_init(). Non-boot pagesets then subsequently update them to the proper >> values. >> >> No functional change. >> >> Signed-off-by: Vlastimil Babka >> --- >> mm/page_alloc.c | 17 ++++++++++------- >> 1 file changed, 10 insertions(+), 7 deletions(-) >> >> diff --git a/mm/page_alloc.c b/mm/page_alloc.c >> index 26069c8d1b19..76c2b4578723 100644 >> --- a/mm/page_alloc.c >> +++ b/mm/page_alloc.c >> @@ -5823,7 +5823,7 @@ static void build_zonelists(pg_data_t *pgdat) >> * not check if the processor is online before following the pageset pointer. >> * Other parts of the kernel may not check if the zone is available. >> */ >> -static void setup_pageset(struct per_cpu_pageset *p); >> +static void pageset_init(struct per_cpu_pageset *p); >> static DEFINE_PER_CPU(struct per_cpu_pageset, boot_pageset); >> static DEFINE_PER_CPU(struct per_cpu_nodestat, boot_nodestats); >> >> @@ -5891,7 +5891,7 @@ build_all_zonelists_init(void) >> * (a chicken-egg dilemma). >> */ >> for_each_possible_cpu(cpu) >> - setup_pageset(&per_cpu(boot_pageset, cpu)); >> + pageset_init(&per_cpu(boot_pageset, cpu)); >> >> mminit_verify_zonelist(); >> cpuset_init_current_mems_allowed(); >> @@ -6210,12 +6210,15 @@ static void pageset_init(struct per_cpu_pageset *p) >> pcp = &p->pcp; >> for (migratetype = 0; migratetype < MIGRATE_PCPTYPES; migratetype++) >> INIT_LIST_HEAD(&pcp->lists[migratetype]); >> -} >> >> -static void setup_pageset(struct per_cpu_pageset *p) >> -{ >> - pageset_init(p); >> - pageset_update(&p->pcp, 0, 1); >> + /* >> + * Set batch and high values safe for a boot pageset. A true percpu >> + * pageset's initialization will update them subsequently. Here we don't >> + * need to be as careful as pageset_update() as nobody can access the >> + * pageset yet. > > Isn't this slightly misleading? pageset_init is called from setup_zone_pageset > which is called from the memory hotplug as well. Isn't this more about It is. > early zone initialization rather than boot pagesets? Or am I misreading > the patch? It's for boot pagesets (call from build_all_zonelists_init()) that we need these particular values (well, just high = 0). For early zone initialization during hotplug the values don't matter as the caller is setup_zone_pageset() who immediately replaces the values by zone_set_pageset_high_and_batch(). Which is what the comment tries to say. >> + */ >> + pcp->high = 0; >> + pcp->batch = 1; >> } >> >> /* >> -- >> 2.28.0 >