From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751559AbdANQjR (ORCPT ); Sat, 14 Jan 2017 11:39:17 -0500 Received: from gum.cmpxchg.org ([85.214.110.215]:37804 "EHLO gum.cmpxchg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751031AbdANQjQ (ORCPT ); Sat, 14 Jan 2017 11:39:16 -0500 Date: Sat, 14 Jan 2017 11:39:08 -0500 From: Johannes Weiner To: Michal Hocko Cc: Andrew Morton , Vlastimil Babka , Hugh Dickins , Mel Gorman , linux-mm@kvack.org, LKML , Michal Hocko Subject: Re: [PATCH] mm, vmscan: do not count freed pages as PGDEACTIVATE Message-ID: <20170114163908.GH26139@cmpxchg.org> References: <20170112211221.17636-1-mhocko@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170112211221.17636-1-mhocko@kernel.org> User-Agent: Mutt/1.7.2 (2016-11-26) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 12, 2017 at 10:12:21PM +0100, Michal Hocko wrote: > From: Michal Hocko > > PGDEACTIVATE represents the number of pages moved from the active list > to the inactive list. At least this sounds like the original motivation > of the counter. move_active_pages_to_lru, however, counts pages which > got freed in the mean time as deactivated as well. This is a very rare > event and counting them as deactivation in itself is not harmful but it > makes the code more convoluted than necessary - we have to count both > all pages and those which are freed which is a bit confusing. > > After this patch the PGDEACTIVATE should have a slightly more clear > semantic and only count those pages which are moved from the active to > the inactive list which is a plus. > > Suggested-by: Vlastimil Babka > Signed-off-by: Michal Hocko I bet it's a small inaccuracy in practice, but now that the trace patches added a proper counter, might as well consolidate into the correct one. Acked-by: Johannes Weiner