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=-8.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 2C07FC2BB84 for ; Thu, 10 Sep 2020 08:32:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CCAA12076C for ; Thu, 10 Sep 2020 08:32:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730576AbgIJIce (ORCPT ); Thu, 10 Sep 2020 04:32:34 -0400 Received: from mx2.suse.de ([195.135.220.15]:39996 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730323AbgIJIb2 (ORCPT ); Thu, 10 Sep 2020 04:31:28 -0400 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 66B26AF43; Thu, 10 Sep 2020 08:31:42 +0000 (UTC) Date: Thu, 10 Sep 2020 10:31:20 +0200 From: Oscar Salvador To: Vlastimil Babka Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Michal Hocko , Pavel Tatashin , David Hildenbrand , Joonsoo Kim Subject: Re: [RFC 1/5] mm, page_alloc: clean up pageset high and batch update Message-ID: <20200910083116.GA2285@linux> References: <20200907163628.26495-1-vbabka@suse.cz> <20200907163628.26495-2-vbabka@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200907163628.26495-2-vbabka@suse.cz> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 07, 2020 at 06:36:24PM +0200, Vlastimil Babka wrote: > Signed-off-by: Vlastimil Babka > for_each_possible_cpu(cpu) > - setup_pageset(&per_cpu(boot_pageset, cpu), 0); > + setup_pageset(&per_cpu(boot_pageset, cpu)); This is not really anything important but I realized we have like 7 functions messing with pcp lists, and everytime I try to follow them my head spins. Since setup_pageset is only being called here, could we replace it by the pageset_init and pageset_update? (As I said, not important and probably a matter of taste. I just think that having so many mini functions around is not always cool, e.g: setup_zone_pageset->zone_pageset_init) > -/* > - * pageset_set_high() sets the high water mark for hot per_cpu_pagelist > - * to the value high for the pageset p. > - */ > -static void pageset_set_high(struct per_cpu_pageset *p, > - unsigned long high) > -{ > - unsigned long batch = max(1UL, high / 4); > - if ((high / 4) > (PAGE_SHIFT * 8)) > - batch = PAGE_SHIFT * 8; > - > - pageset_update(&p->pcp, high, batch); > + pageset_update(&p->pcp, 0, 1); > } Could we restore the comment we had in pageset_set_high, and maybe update it to match this new function? I think it would be useful. > > static void pageset_set_high_and_batch(struct zone *zone, > - struct per_cpu_pageset *pcp) > + struct per_cpu_pageset *p) > { > - if (percpu_pagelist_fraction) > - pageset_set_high(pcp, > - (zone_managed_pages(zone) / > - percpu_pagelist_fraction)); > - else > - pageset_set_batch(pcp, zone_batchsize(zone)); > + unsigned long new_high; > + unsigned long new_batch; > + int fraction = READ_ONCE(percpu_pagelist_fraction); Why the READ_ONCE? In case there is a parallel update so things to get messed up? as I said, I'd appreciate a comment in pageset_set_high_and_batch to be restored and updated, otherwise: Reviewed-by: Oscar Salvador Thanks -- Oscar Salvador SUSE L3