From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with ESMTP id D175B6B0069 for ; Wed, 2 Nov 2011 14:04:40 -0400 (EDT) Message-ID: <4EB1862E.8070401@jp.fujitsu.com> Date: Wed, 02 Nov 2011 11:04:30 -0700 From: KOSAKI Motohiro MIME-Version: 1.0 Subject: Re: [rfc 2/3] mm: vmscan: treat inactive cycling as neutral References: <20110808110658.31053.55013.stgit@localhost6> <4E3FD403.6000400@parallels.com> <20111102163056.GG19965@redhat.com> <20111102163213.GI19965@redhat.com> In-Reply-To: <20111102163213.GI19965@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: jweiner@redhat.com Cc: khlebnikov@parallels.com, penberg@kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, fengguang.wu@intel.com, kamezawa.hiroyu@jp.fujitsu.com, hannes@cmpxchg.org, riel@redhat.com, mel@csn.ul.ie, minchan.kim@gmail.com, gene.heskett@gmail.com (11/2/2011 9:32 AM), Johannes Weiner wrote: > Each page that is scanned but put back to the inactive list is counted > as a successful reclaim, which tips the balance between file and anon > lists more towards the cycling list. > > This does - in my opinion - not make too much sense, but at the same > time it was not much of a problem, as the conditions that lead to an > inactive list cycle were mostly temporary - locked page, concurrent > page table changes, backing device congested - or at least limited to > a single reclaimer that was not allowed to unmap or meddle with IO. > More important than being moderately rare, those conditions should > apply to both anon and mapped file pages equally and balance out in > the end. > > Recently, we started cycling file pages in particular on the inactive > list much more aggressively, for used-once detection of mapped pages, > and when avoiding writeback from direct reclaim. > > Those rotated pages do not exactly speak for the reclaimability of the > list they sit on and we risk putting immense pressure on file list for > no good reason. > > Instead, count each page not reclaimed and put back to any list, > active or inactive, as rotated, so they are neutral with respect to > the scan/rotate ratio of the list class, as they should be. > > Signed-off-by: Johannes Weiner > --- > mm/vmscan.c | 9 ++++----- > 1 files changed, 4 insertions(+), 5 deletions(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 39d3da3..6da66a7 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -1360,7 +1360,9 @@ putback_lru_pages(struct zone *zone, struct scan_control *sc, > */ > spin_lock(&zone->lru_lock); > while (!list_empty(page_list)) { > + int file; > int lru; > + > page = lru_to_page(page_list); > VM_BUG_ON(PageLRU(page)); > list_del(&page->lru); > @@ -1373,11 +1375,8 @@ putback_lru_pages(struct zone *zone, struct scan_control *sc, > SetPageLRU(page); > lru = page_lru(page); > add_page_to_lru_list(zone, page, lru); > - if (is_active_lru(lru)) { > - int file = is_file_lru(lru); > - int numpages = hpage_nr_pages(page); > - reclaim_stat->recent_rotated[file] += numpages; > - } > + file = is_file_lru(lru); > + reclaim_stat->recent_rotated[file] += hpage_nr_pages(page); > if (!pagevec_add(&pvec, page)) { > spin_unlock_irq(&zone->lru_lock); > __pagevec_release(&pvec); When avoiding writeback from direct reclaim case, I think we shouldn't increase recent_rotated because VM decided "the page should be eviceted, but also it should be delayed". i'm not sure it's minor factor or not. -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org