From mboxrd@z Thu Jan 1 00:00:00 1970 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752533AbeAESJJ (ORCPT + 1 other); Fri, 5 Jan 2018 13:09:09 -0500 Received: from mx2.suse.de ([195.135.220.15]:43763 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752063AbeAESJI (ORCPT ); Fri, 5 Jan 2018 13:09:08 -0500 Date: Fri, 5 Jan 2018 19:09:05 +0100 From: Michal Hocko To: Christopher Lameter Cc: Anshuman Khandual , Andrew Morton , Zi Yan , Naoya Horiguchi , "Kirill A. Shutemov" , Vlastimil Babka , Andrea Reale , linux-mm@kvack.org, LKML Subject: Re: [PATCH 1/3] mm, numa: rework do_pages_move Message-ID: <20180105180905.GR2801@dhcp22.suse.cz> References: <20180103082555.14592-1-mhocko@kernel.org> <20180103082555.14592-2-mhocko@kernel.org> <20180105091443.GJ2801@dhcp22.suse.cz> <20180105093301.GK2801@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: On Fri 05-01-18 11:15:18, Cristopher Lameter wrote: > On Fri, 5 Jan 2018, Michal Hocko wrote: > > > Yes. I am really wondering because there souldn't anything specific to > > improve the situation with patch 2 and 3. Likewise the only overhead > > from the patch 1 I can see is the reduced batching of the mmap_sem. But > > then I am wondering what would compensate that later... > > Could you reduce the frequency of taking mmap_sem? Maybe take it when > picking a new node and drop it when done with that node before migrating > the list of pages? I believe there should be some cap on the number of pages. We shouldn't keep it held for million of pages if all of them are moved to the same node. I would really like to postpone that to later unless it causes some noticeable regressions because this would complicate the code further and I am not sure this is all worth it. -- Michal Hocko SUSE Labs