From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756116Ab2CJAEy (ORCPT ); Fri, 9 Mar 2012 19:04:54 -0500 Received: from mail-iy0-f174.google.com ([209.85.210.174]:58141 "EHLO mail-iy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753511Ab2CJAEw (ORCPT ); Fri, 9 Mar 2012 19:04:52 -0500 Date: Fri, 9 Mar 2012 16:04:18 -0800 (PST) From: Hugh Dickins X-X-Sender: hugh@eggly.anvils To: Konstantin Khlebnikov cc: KAMEZAWA Hiroyuki , Andrew Morton , Johannes Weiner , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH 3/7 v2] mm: rework __isolate_lru_page() file/anon filter In-Reply-To: <4F59AE3C.5040200@openvz.org> Message-ID: References: <20120229091547.29236.28230.stgit@zurg> <20120303091327.17599.80336.stgit@zurg> <20120308143034.f3521b1e.kamezawa.hiroyu@jp.fujitsu.com> <4F59AE3C.5040200@openvz.org> User-Agent: Alpine 2.00 (LSU 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 9 Mar 2012, Konstantin Khlebnikov wrote: > Hugh Dickins wrote: > > > > I like very much the look of what he's come up with, but I'm still > > puzzling over why it barely makes any improvement to __isolate_lru_page(): > > seems significantly inferior (in code size terms) to his original (which > > I imagine Glauber's compromise would be equivalent to). > > > > At some point I ought to give up on niggling about this, > > but I haven't quite got there yet. > > (with if()) > $ ./scripts/bloat-o-meter built-in.o built-in.o-v1 > add/remove: 0/0 grow/shrink: 2/1 up/down: 32/-20 (12) > function old new delta > static.shrink_active_list 837 853 +16 > shrink_inactive_list 1259 1275 +16 > static.isolate_lru_pages 1055 1035 -20 > > (with switch()) > $ ./scripts/bloat-o-meter built-in.o built-in.o-v2 > add/remove: 0/0 grow/shrink: 4/2 up/down: 111/-23 (88) > function old new delta > __isolate_lru_page 301 377 +76 > static.shrink_active_list 837 853 +16 > shrink_inactive_list 1259 1275 +16 > page_evictable 170 173 +3 > __remove_mapping 322 319 -3 > static.isolate_lru_pages 1055 1035 -20 > > (without __always_inline on page_lru()) > $ ./scripts/bloat-o-meter built-in.o built-in.o-v5-noinline > add/remove: 0/0 grow/shrink: 5/2 up/down: 93/-23 (70) > function old new delta > __isolate_lru_page 301 333 +32 > isolate_lru_page 359 385 +26 > static.shrink_active_list 837 853 +16 > putback_inactive_pages 635 651 +16 > page_evictable 170 173 +3 > __remove_mapping 322 319 -3 > static.isolate_lru_pages 1055 1035 -20 > > $ ./scripts/bloat-o-meter built-in.o built-in.o-v5 > add/remove: 0/0 grow/shrink: 3/4 up/down: 35/-67 (-32) > function old new delta > static.shrink_active_list 837 853 +16 > __isolate_lru_page 301 317 +16 > page_evictable 170 173 +3 > __remove_mapping 322 319 -3 > mem_cgroup_lru_del 73 65 -8 > static.isolate_lru_pages 1055 1035 -20 > __mem_cgroup_commit_charge 676 640 -36 > > Actually __isolate_lru_page() even little bit bigger I was coming to realize that it must be your page_lru()ing: although it's dressed up in one line, there's several branches there. I think you'll find you have a clear winner at last, if you just pass lru on down as third arg to __isolate_lru_page(), where file used to be passed, instead of re-evaluating it inside. shrink callers already have the lru, and compaction works it out immediately afterwards. Though we do need to be careful: the lumpy case would then have to pass page_lru(cursor_page). Oh, actually no (though it would deserve a comment): since the lumpy case selects LRU_ALL_EVICTABLE, it's irrelevant what it passes for lru, so might as well stick with the one passed down. Though you may decide I'm being too tricky there, and prefer to calculate page_lru(cursor_page) anyway, it not being the hottest path. Whether you'd still want page_lru(page) __always_inline, I don't know. Hugh