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,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, USER_AGENT_SANE_1 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 65166C4727D for ; Mon, 5 Oct 2020 13:28:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1862820774 for ; Mon, 5 Oct 2020 13:28:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="krA5UWKl" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726032AbgJEN2f (ORCPT ); Mon, 5 Oct 2020 09:28:35 -0400 Received: from mx2.suse.de ([195.135.220.15]:50568 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725914AbgJEN2f (ORCPT ); Mon, 5 Oct 2020 09:28:35 -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=1601904513; 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=IPqPNbDqClbP8EksYsOoKg3cRZhaMTz9vJe273I/bK0=; b=krA5UWKlDkZ8d6gQzz6GVnSDlOTpq8O4pe01xbORAvttEp0Gzw71JSEInos1S4atPTME/n 9Y0tAZeKgGDZ+xA6yFopD4TuC79/IY3EgltPVyucHOz7CTngy7EFAGNe/hQLrvZ+CXWO7F SDn0q2jTm7UQh+npH5kFG/M490rvevU= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 70346ACD8; Mon, 5 Oct 2020 13:28:33 +0000 (UTC) Date: Mon, 5 Oct 2020 15:28:30 +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 6/9] mm, page_alloc: cache pageset high and batch in struct zone Message-ID: <20201005132830.GB4555@dhcp22.suse.cz> References: <20200922143712.12048-1-vbabka@suse.cz> <20200922143712.12048-7-vbabka@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200922143712.12048-7-vbabka@suse.cz> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 22-09-20 16:37:09, Vlastimil Babka wrote: > All per-cpu pagesets for a zone use the same high and batch values, that are > duplicated there just for performance (locality) reasons. This patch adds the > same variables also to struct zone as a shared copy. > > This will be useful later for making possible to disable pcplists temporarily > by setting high value to 0, while remembering the values for restoring them > later. But we can also immediately benefit from not updating pagesets of all > possible cpus in case the newly recalculated values (after sysctl change or > memory online/offline) are actually unchanged from the previous ones. Advantage of this patch is not really clear from it in isolation. Maybe merge it with the patch which uses the duplicated state. > > Signed-off-by: Vlastimil Babka > --- > include/linux/mmzone.h | 6 ++++++ > mm/page_alloc.c | 16 ++++++++++++++-- > 2 files changed, 20 insertions(+), 2 deletions(-) > > diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h > index 90721f3156bc..7ad3f14dbe88 100644 > --- a/include/linux/mmzone.h > +++ b/include/linux/mmzone.h > @@ -470,6 +470,12 @@ struct zone { > #endif > struct pglist_data *zone_pgdat; > struct per_cpu_pageset __percpu *pageset; > + /* > + * the high and batch values are copied to individual pagesets for > + * faster access > + */ > + int pageset_high; > + int pageset_batch; > > #ifndef CONFIG_SPARSEMEM > /* > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index de3b48bda45c..901907799bdc 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -5824,6 +5824,8 @@ static void build_zonelists(pg_data_t *pgdat) > * Other parts of the kernel may not check if the zone is available. > */ > static void pageset_init(struct per_cpu_pageset *p); > +#define BOOT_PAGESET_HIGH 0 > +#define BOOT_PAGESET_BATCH 1 > static DEFINE_PER_CPU(struct per_cpu_pageset, boot_pageset); > static DEFINE_PER_CPU(struct per_cpu_nodestat, boot_nodestats); > > @@ -6213,8 +6215,8 @@ static void pageset_init(struct per_cpu_pageset *p) > * need to be as careful as pageset_update() as nobody can access the > * pageset yet. > */ > - pcp->high = 0; > - pcp->batch = 1; > + pcp->high = BOOT_PAGESET_HIGH; > + pcp->batch = BOOT_PAGESET_BATCH; > } > > /* > @@ -6238,6 +6240,14 @@ static void zone_set_pageset_high_and_batch(struct zone *zone) > new_batch = max(1UL, 1 * new_batch); > } > > + if (zone->pageset_high != new_high || > + zone->pageset_batch != new_batch) { > + zone->pageset_high = new_high; > + zone->pageset_batch = new_batch; > + } else { > + return; > + } > + > for_each_possible_cpu(cpu) { > p = per_cpu_ptr(zone->pageset, cpu); > pageset_update(&p->pcp, new_high, new_batch); > @@ -6300,6 +6310,8 @@ static __meminit void zone_pcp_init(struct zone *zone) > * offset of a (static) per cpu variable into the per cpu area. > */ > zone->pageset = &boot_pageset; > + zone->pageset_high = BOOT_PAGESET_HIGH; > + zone->pageset_batch = BOOT_PAGESET_BATCH; > > if (populated_zone(zone)) > printk(KERN_DEBUG " %s zone: %lu pages, LIFO batch:%u\n", > -- > 2.28.0 -- Michal Hocko SUSE Labs