From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S968209AbdADPJy (ORCPT ); Wed, 4 Jan 2017 10:09:54 -0500 Received: from mx2.suse.de ([195.135.220.15]:44235 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S968194AbdADPJv (ORCPT ); Wed, 4 Jan 2017 10:09:51 -0500 Date: Wed, 4 Jan 2017 16:09:47 +0100 From: Michal Hocko To: Vlastimil Babka Cc: Andrew Morton , Mel Gorman , Johannes Weiner , Minchan Kim , Hillf Danton , linux-mm@kvack.org, LKML Subject: Re: [PATCH 5/7] mm, vmscan: extract shrink_page_list reclaim counters into a struct Message-ID: <20170104150947.GP25453@dhcp22.suse.cz> References: <20170104101942.4860-1-mhocko@kernel.org> <20170104101942.4860-6-mhocko@kernel.org> <01c9e2c9-3a04-48cd-cf0e-265db33d1a24@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <01c9e2c9-3a04-48cd-cf0e-265db33d1a24@suse.cz> User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 04-01-17 15:51:43, Vlastimil Babka wrote: [...] > > @@ -1266,11 +1270,13 @@ static unsigned long shrink_page_list(struct list_head *page_list, > > list_splice(&ret_pages, page_list); > > count_vm_events(PGACTIVATE, pgactivate); > > > > - *ret_nr_dirty += nr_dirty; > > - *ret_nr_congested += nr_congested; > > - *ret_nr_unqueued_dirty += nr_unqueued_dirty; > > - *ret_nr_writeback += nr_writeback; > > - *ret_nr_immediate += nr_immediate; > > + if (stat) { > > + stat->nr_dirty = nr_dirty; > > + stat->nr_congested = nr_congested; > > + stat->nr_unqueued_dirty = nr_unqueued_dirty; > > + stat->nr_writeback = nr_writeback; > > + stat->nr_immediate = nr_immediate; > > + } > > This change of '+=' to '=' raised my eybrows, but it seems both callers > don't care so this is indeed no functional change and potentially faster. Yes, I was quite surprised as well, maybe we had a code which relied on the aggregated numbers in the past but I didn't bother to go over git logs to check. There is no such user anymore... -- Michal Hocko SUSE Labs