From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f173.google.com (mail-pd0-f173.google.com [209.85.192.173]) by kanga.kvack.org (Postfix) with ESMTP id BDC6E6B013E for ; Tue, 10 Jun 2014 23:23:04 -0400 (EDT) Received: by mail-pd0-f173.google.com with SMTP id v10so6721017pde.18 for ; Tue, 10 Jun 2014 20:23:04 -0700 (PDT) Received: from mail-pd0-x232.google.com (mail-pd0-x232.google.com [2607:f8b0:400e:c02::232]) by mx.google.com with ESMTPS id ky7si36461125pbc.146.2014.06.10.20.23.03 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 10 Jun 2014 20:23:03 -0700 (PDT) Received: by mail-pd0-f178.google.com with SMTP id v10so6736424pde.37 for ; Tue, 10 Jun 2014 20:23:03 -0700 (PDT) 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 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" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: mgorman@suse.de, mhocko@suse.cz, hannes@cmpxchg.org, linux-mm@kvack.org, 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, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org