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=-9.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 0A2ECC43467 for ; Thu, 8 Oct 2020 12:23:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A39EF20659 for ; Thu, 8 Oct 2020 12:23:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="T+nFtKLT" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729794AbgJHMXM (ORCPT ); Thu, 8 Oct 2020 08:23:12 -0400 Received: from mx2.suse.de ([195.135.220.15]:58702 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729722AbgJHMXM (ORCPT ); Thu, 8 Oct 2020 08:23:12 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1602159790; 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=TtXgBFrg0rFqKIY1cOlrbxSoEXaREYSY+5dIWTCP/uM=; b=T+nFtKLTGTJrJBoydciXFCQzl450l+Ulqo4gBD9IFFKY4UF184At1sa+KdiPJi6sct3ZDq iYaRmD2G1RICLXNumJD3jdjbkiH8z2tfORxxZ4nefA0qvJ4Ir9aXWzHObcHsDSjbK1t1Fa aEakux03USysNhD4nyySam+UyYWgP3A= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id A5E92AEF8; Thu, 8 Oct 2020 12:23:10 +0000 (UTC) Date: Thu, 8 Oct 2020 14:23:09 +0200 From: Michal Hocko To: Vlastimil Babka Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Pavel Tatashin , David Hildenbrand , Oscar Salvador , Joonsoo Kim Subject: Re: [PATCH v2 3/7] mm, page_alloc: remove setup_pageset() Message-ID: <20201008122309.GB4967@dhcp22.suse.cz> References: <20201008114201.18824-1-vbabka@suse.cz> <20201008114201.18824-4-vbabka@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201008114201.18824-4-vbabka@suse.cz> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 08-10-20 13:41:57, 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 > Reviewed-by: David Hildenbrand Acked-by: Michal Hocko Btw. where do we initialize pcp->count? I thought that pcp allocator zeroes out the allocated memory but alloc_percpu is GFP_KERNEL like. > --- > 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 463f40b12aca..f827b42a2475 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -5899,7 +5899,7 @@ 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); > > @@ -5967,7 +5967,7 @@ 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(); > @@ -6286,12 +6286,15 @@ 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. > + */ > + pcp->high = 0; > + pcp->batch = 1; > } > > /* > -- > 2.28.0 -- Michal Hocko SUSE Labs