Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755282AbaFKDXF (ORCPT ); Tue, 10 Jun 2014 23:23:05 -0400 Received: from mail-pd0-f171.google.com ([209.85.192.171]:53950 "EHLO mail-pd0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754961AbaFKDXD (ORCPT ); Tue, 10 Jun 2014 23:23:03 -0400 Message-ID: <1402456897.28433.46.camel@debian> Subject: Re: [PATCH] mm/vmscan.c: avoid recording the original scan targets in shrink_lruvec() From: Chen Yucong To: Andrew Morton Cc: mgorman@suse.de, mhocko@suse.cz, hannes@cmpxchg.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Date: Wed, 11 Jun 2014 11:21:37 +0800 In-Reply-To: <20140610163338.5b463c5884c4c7e3f1b948e2@linux-foundation.org> References: <1402320436-22270-1-git-send-email-slaoub@gmail.com> <20140610163338.5b463c5884c4c7e3f1b948e2@linux-foundation.org> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.4.4-3 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2014-06-10 at 16:33 -0700, Andrew Morton wrote: > > break; > > > > if (nr_file > nr_anon) { > > - unsigned long scan_target = > targets[LRU_INACTIVE_ANON] + > > > - targets[LRU_ACTIVE_ANON] > + 1; > > + nr_to_scan = nr_file - ratio * nr_anon; > > + percentage = nr[LRU_FILE] * 100 / nr_file; > > here, nr_file and nr_anon are derived from the contents of nr[]. But > nr[] was modified in the for_each_evictable_lru() loop, so its > contents > now may differ from what was in targets[]? nr_to_scan is used for recording the number of pages that should be scanned to keep original *ratio*. We can assume that the value of (nr_file > nr_anon) is true, nr_to_scan should be distribute to nr[LRU_ACTIVE_FILE] and nr[LRU_INACTIVE_FILE] in proportion. nr_file = nr[LRU_ACTIVE_FILE] + nr[LRU_INACTIVE_FILE]; percentage = nr[LRU_FILE] / nr_file; Note that in comparison with *old* percentage, the "new" percentage has the different meaning. It is just used to divide nr_so_scan pages appropriately. thx! cyc -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/