From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f54.google.com (mail-pa0-f54.google.com [209.85.220.54]) by kanga.kvack.org (Postfix) with ESMTP id 87D446B0031 for ; Wed, 18 Jun 2014 20:07:14 -0400 (EDT) Received: by mail-pa0-f54.google.com with SMTP id et14so1264460pad.27 for ; Wed, 18 Jun 2014 17:07:14 -0700 (PDT) Received: from mail-pa0-x230.google.com (mail-pa0-x230.google.com [2607:f8b0:400e:c03::230]) by mx.google.com with ESMTPS id cc2si3736489pbb.208.2014.06.18.17.07.13 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Wed, 18 Jun 2014 17:07:13 -0700 (PDT) Received: by mail-pa0-f48.google.com with SMTP id et14so1259591pad.7 for ; Wed, 18 Jun 2014 17:07:13 -0700 (PDT) Message-ID: <1403136272.12954.4.camel@debian> Subject: Re: [PATCH] mm/vmscan.c: fix an implementation flaw in proportional scanning From: Chen Yucong Date: Thu, 19 Jun 2014 08:04:32 +0800 In-Reply-To: <20140618152751.283deda95257cc32ccea8f20@linux-foundation.org> References: <1402980902-6345-1-git-send-email-slaoub@gmail.com> <20140618152751.283deda95257cc32ccea8f20@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: minchan@kernel.org, mgorman@suse.de, hannes@cmpxchg.org, mhocko@suse.cz, riel@redhat.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org On Wed, 2014-06-18 at 15:27 -0700, Andrew Morton wrote: > On Tue, 17 Jun 2014 12:55:02 +0800 Chen Yucong wrote: > > > diff --git a/mm/vmscan.c b/mm/vmscan.c > > index a8ffe4e..2c35e34 100644 > > --- a/mm/vmscan.c > > +++ b/mm/vmscan.c > > @@ -2087,8 +2086,8 @@ static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc) > > blk_start_plug(&plug); > > while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] || > > nr[LRU_INACTIVE_FILE]) { > > - unsigned long nr_anon, nr_file, percentage; > > - unsigned long nr_scanned; > > + unsigned long nr_anon, nr_file, file_percent, anon_percent; > > + unsigned long nr_to_scan, nr_scanned, percentage; > > > > for_each_evictable_lru(lru) { > > if (nr[lru]) { > > The increased stack use is a slight concern - we can be very deep here. > I suspect the "percent" locals are more for convenience/clarity, and > they could be eliminated (in a separate patch) at some cost of clarity? > diff --git a/mm/vmscan.c b/mm/vmscan.c index a8ffe4e..2c35e34 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2057,8 +2057,7 @@ out: static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc) { unsigned long nr[NR_LRU_LISTS]; - unsigned long targets[NR_LRU_LISTS]; - unsigned long nr_to_scan; + unsigned long file_target, anon_target; >>From the above snippet, we can know that the "percent" locals come from targets[NR_LRU_LISTS]. So this fix does not increase the stack. 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