From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752221AbbANXew (ORCPT ); Wed, 14 Jan 2015 18:34:52 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:43482 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751221AbbANXev (ORCPT ); Wed, 14 Jan 2015 18:34:51 -0500 Date: Wed, 14 Jan 2015 15:34:49 -0800 From: Andrew Morton To: Vladimir Davydov Cc: Johannes Weiner , Michal Hocko , Vlastimil Babka , Mel Gorman , Rik van Riel , , Subject: Re: [PATCH -mm] vmscan: move reclaim_state handling to shrink_slab Message-Id: <20150114153449.038bc61b1bd6fc262f9cea01@linux-foundation.org> In-Reply-To: <1421243736-21367-1-git-send-email-vdavydov@parallels.com> References: <1421243736-21367-1-git-send-email-vdavydov@parallels.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 Wed, 14 Jan 2015 16:55:36 +0300 Vladimir Davydov wrote: > current->reclaim_state is only used to count the number of slab pages > reclaimed by shrink_slab(). So instead of initializing it before we are > going to call try_to_free_pages() or shrink_zone(), let's set in > directly in shrink_slab(). > > This patch also makes shrink_slab() return the number of reclaimed slab > pages (obtained from reclaim_state) instead of the number of reclaimed > objects, because the latter is not of much use - it was only checked by > drop_slab() to decide whether it should continue reclaim or abort. The > number of reclaimed pages is more appropriate, because it also can be > used by shrink_zone() to accumulate scan_control->nr_reclaimed. Not sure that this is a good change. If shrink_slab() managed to free some objects but didn't free any pages then that's a good sign that additional calls to shrink_slab() *will* free some pages. With this change, drop_slab_node() can give up too early. The general philosophy throughout here is: "pass it nr_to_scan, it returns nr_scanned/nr_freed". Switching the return value to nr_pages_freed kinda breaks that paradigm. > Note that after this patch try_to_free_mem_cgroup_pages() will count not > only reclaimed user pages, but also slab pages, which is expected, > because it can reclaim kmem from kmem-active sub cgroups. > > mm/page_alloc.c | 4 --- > mm/vmscan.c | 73 ++++++++++++++++++++----------------------------------- > 2 files changed, 27 insertions(+), 50 deletions(-) That's nice though.