From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752142AbcFNWOa (ORCPT ); Tue, 14 Jun 2016 18:14:30 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:55895 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751150AbcFNWO3 (ORCPT ); Tue, 14 Jun 2016 18:14:29 -0400 Date: Tue, 14 Jun 2016 15:14:26 -0700 From: Andrew Morton To: Cc: , , , , , , , , , , Hugh Dickins Subject: Re: [PATCH] more mapcount page as kpage could reduce total replacement times than fewer mapcount one in probability. Message-Id: <20160614151426.0e893a1f7b4e549a7c6e7fdf@linux-foundation.org> In-Reply-To: <1465895857-1515-1-git-send-email-zhouxianrong@huawei.com> References: <1465895857-1515-1-git-send-email-zhouxianrong@huawei.com> X-Mailer: Sylpheed 3.4.1 (GTK+ 2.24.23; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 14 Jun 2016 17:17:37 +0800 wrote: > From: z00281421 > > more mapcount page as kpage could reduce total replacement > times than fewer mapcount one when ksmd scan and replace > among forked pages later. > Hopefully Hugh will be able to have a think about this. > --- a/mm/ksm.c > +++ b/mm/ksm.c > @@ -1094,6 +1094,21 @@ static struct page *try_to_merge_two_pages(struct rmap_item *rmap_item, > { > int err; > > + /* > + * select more mapcount page as kpage > + */ > + if (page_mapcount(page) < page_mapcount(tree_page)) { > + struct page *tmp_page; > + struct rmap_item *tmp_rmap_item; > + > + tmp_page = page; > + page = tree_page; > + tree_page = tmp_page; > + tmp_rmap_item = rmap_item; > + rmap_item = tree_rmap_item; > + tree_rmap_item = tmp_rmap_item; > + } kernel.h provides a swap() macro. > err = try_to_merge_with_ksm_page(rmap_item, page, NULL); > if (!err) { > err = try_to_merge_with_ksm_page(tree_rmap_item,