From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754445AbaFNDG3 (ORCPT ); Fri, 13 Jun 2014 23:06:29 -0400 Received: from mail-pa0-f53.google.com ([209.85.220.53]:63365 "EHLO mail-pa0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754050AbaFNDG1 (ORCPT ); Fri, 13 Jun 2014 23:06:27 -0400 Message-ID: <1402715082.750.13.camel@debian> Subject: Re: [PATCH v2] mm/vmscan.c: wrap five parameters into shrink_result for reducing the stack consumption From: Chen Yucong To: Johannes Weiner Cc: Andrew Morton , mgorman@suse.de, mhocko@suse.cz, riel@redhat.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Date: Sat, 14 Jun 2014 11:04:42 +0800 In-Reply-To: <20140613162807.GP2878@cmpxchg.org> References: <1402634191-3442-1-git-send-email-slaoub@gmail.com> <20140612214016.1beda952.akpm@linux-foundation.org> <1402636875.1232.13.camel@debian> <20140613162807.GP2878@cmpxchg.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 Fri, 2014-06-13 at 12:28 -0400, Johannes Weiner wrote: > On Fri, Jun 13, 2014 at 01:21:15PM +0800, Chen Yucong wrote: > > On Thu, 2014-06-12 at 21:40 -0700, Andrew Morton wrote: > > > On Fri, 13 Jun 2014 12:36:31 +0800 Chen Yucong wrote: > > > > > > > @@ -1148,7 +1146,8 @@ unsigned long reclaim_clean_pages_from_list(struct zone *zone, > > > > .priority = DEF_PRIORITY, > > > > .may_unmap = 1, > > > > }; > > > > - unsigned long ret, dummy1, dummy2, dummy3, dummy4, dummy5; > > > > + unsigned long ret; > > > > + struct shrink_result dummy = { }; > > > > > > You didn't like the idea of making this static? > > Sorry! It's my negligence. > > If we make dummy static, it can help us save more stack. > > > > without change: > > 0xffffffff810aede8 reclaim_clean_pages_from_list []: 184 > > 0xffffffff810aeef8 reclaim_clean_pages_from_list []: 184 > > > > with change: struct shrink_result dummy = {}; > > 0xffffffff810aed6c reclaim_clean_pages_from_list []: 152 > > 0xffffffff810aee68 reclaim_clean_pages_from_list []: 152 > > > > with change: static struct shrink_result dummy ={}; > > 0xffffffff810aed69 reclaim_clean_pages_from_list []: 120 > > 0xffffffff810aee4d reclaim_clean_pages_from_list []: 120 > > FWIW, I copied bloat-o-meter and hacked up a quick comparison tool > that you can feed two outputs of checkstack.pl for a whole vmlinux and > it shows you the delta. > > The output for your patch (with the static dummy) looks like this: > > +0/-240 -240 > shrink_inactive_list 136 112 -24 > shrink_page_list 208 160 -48 > reclaim_clean_pages_from_list 168 - -168 > > (The stack footprint for reclaim_clean_pages_from_list is actually 96 > after your patch, but checkstack.pl skips frames under 100) > Thanks very much for your comparison tool. Its output is more concise. thx! cyc gcc version 4.7.3 (Gentoo 4.7.3-r1 p1.4, pie-0.5.5) kernel version 3.15(stable) Intel(R) Core(TM)2 Duo CPU T5670 @ 1.80GHz The output for this patch (with the static dummy) is: +0/-144 -144 shrink_inactive_list 152 120 -32 shrink_page_list 232 184 -48 reclaim_clean_pages_from_list 184 120 -64 ------- gcc version 4.7.2 (Debian 4.7.2-5) kernel version 3.15(stable) Intel(R) Core(TM) i5-2320 CPU @ 3.00GHz The output for this patch (with the static dummy) is: shrink_inactive_list 136 120 -16 shrink_page_list 216 168 -48 reclaim_clean_pages_from_list 184 120 -64