From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ed1-f70.google.com (mail-ed1-f70.google.com [209.85.208.70]) by kanga.kvack.org (Postfix) with ESMTP id 0CC306B0003 for ; Mon, 12 Nov 2018 03:09:29 -0500 (EST) Received: by mail-ed1-f70.google.com with SMTP id t2so1371378edb.22 for ; Mon, 12 Nov 2018 00:09:28 -0800 (PST) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id y2-v6si282812ejq.177.2018.11.12.00.09.27 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 12 Nov 2018 00:09:27 -0800 (PST) Date: Mon, 12 Nov 2018 09:09:26 +0100 From: Michal Hocko Subject: Re: [PATCH] mm, page_alloc: skip zone who has no managed_pages in calculate_totalreserve_pages() Message-ID: <20181112080926.GA14987@dhcp22.suse.cz> References: <20181112071404.13620-1-richard.weiyang@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181112071404.13620-1-richard.weiyang@gmail.com> Sender: owner-linux-mm@kvack.org List-ID: To: Wei Yang Cc: akpm@linux-foundation.org, mgorman@techsingularity.net, linux-mm@kvack.org On Mon 12-11-18 15:14:04, Wei Yang wrote: > Zone with no managed_pages doesn't contribute totalreserv_pages. And the > more nodes we have, the more empty zones there are. > > This patch skip the zones to save some cycles. What is the motivation for the patch? Does it really cause any measurable difference in performance? > Signed-off-by: Wei Yang > --- > mm/page_alloc.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index a919ba5cb3c8..567de15e1106 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -7246,6 +7246,9 @@ static void calculate_totalreserve_pages(void) > struct zone *zone = pgdat->node_zones + i; > long max = 0; > > + if (!managed_zone(zone)) > + continue; > + > /* Find valid and maximum lowmem_reserve in the zone */ > for (j = i; j < MAX_NR_ZONES; j++) { > if (zone->lowmem_reserve[j] > max) > -- > 2.15.1 > -- Michal Hocko SUSE Labs