From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f173.google.com (mail-io0-f173.google.com [209.85.223.173]) by kanga.kvack.org (Postfix) with ESMTP id 1F7046B025C for ; Thu, 28 Jan 2016 22:42:16 -0500 (EST) Received: by mail-io0-f173.google.com with SMTP id f81so76740048iof.0 for ; Thu, 28 Jan 2016 19:42:16 -0800 (PST) Received: from us-alimail-mta1.hst.scl.en.alidc.net (mail113-251.mail.alibaba.com. [205.204.113.251]) by mx.google.com with ESMTP id 138si23314670ioc.9.2016.01.28.19.42.13 for ; Thu, 28 Jan 2016 19:42:15 -0800 (PST) Reply-To: "Hillf Danton" From: "Hillf Danton" References: <1450203586-10959-1-git-send-email-mhocko@kernel.org> <1454015979-9985-1-git-send-email-mhocko@kernel.org> In-Reply-To: <1454015979-9985-1-git-send-email-mhocko@kernel.org> Subject: Re: [PATCH 5/3] mm, vmscan: make zone_reclaimable_pages more precise Date: Fri, 29 Jan 2016 11:41:53 +0800 Message-ID: <05f101d15a46$fef53b70$fcdfb250$@alibaba-inc.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Content-Language: zh-cn Sender: owner-linux-mm@kvack.org List-ID: To: 'Michal Hocko' , 'Andrew Morton' Cc: 'Linus Torvalds' , 'Johannes Weiner' , 'Mel Gorman' , 'David Rientjes' , 'Tetsuo Handa' , 'KAMEZAWA Hiroyuki' , linux-mm@kvack.org, 'LKML' , 'Michal Hocko' > > From: Michal Hocko > > zone_reclaimable_pages is used in should_reclaim_retry which uses it to > calculate the target for the watermark check. This means that precise > numbers are important for the correct decision. zone_reclaimable_pages > uses zone_page_state which can contain stale data with per-cpu diffs > not synced yet (the last vmstat_update might have run 1s in the past). > > Use zone_page_state_snapshot in zone_reclaimable_pages instead. None > of the current callers is in a hot path where getting the precise value > (which involves per-cpu iteration) would cause an unreasonable overhead. > > Suggested-by: David Rientjes > Signed-off-by: Michal Hocko > --- Acked-by: Hillf Danton > mm/vmscan.c | 14 +++++++------- > 1 file changed, 7 insertions(+), 7 deletions(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 489212252cd6..9145e3f89eab 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -196,21 +196,21 @@ unsigned long zone_reclaimable_pages(struct zone *zone) > { > unsigned long nr; > > - nr = zone_page_state(zone, NR_ACTIVE_FILE) + > - zone_page_state(zone, NR_INACTIVE_FILE) + > - zone_page_state(zone, NR_ISOLATED_FILE); > + nr = zone_page_state_snapshot(zone, NR_ACTIVE_FILE) + > + zone_page_state_snapshot(zone, NR_INACTIVE_FILE) + > + zone_page_state_snapshot(zone, NR_ISOLATED_FILE); > > if (get_nr_swap_pages() > 0) > - nr += zone_page_state(zone, NR_ACTIVE_ANON) + > - zone_page_state(zone, NR_INACTIVE_ANON) + > - zone_page_state(zone, NR_ISOLATED_ANON); > + nr += zone_page_state_snapshot(zone, NR_ACTIVE_ANON) + > + zone_page_state_snapshot(zone, NR_INACTIVE_ANON) + > + zone_page_state_snapshot(zone, NR_ISOLATED_ANON); > > return nr; > } > > bool zone_reclaimable(struct zone *zone) > { > - return zone_page_state(zone, NR_PAGES_SCANNED) < > + return zone_page_state_snapshot(zone, NR_PAGES_SCANNED) < > zone_reclaimable_pages(zone) * 6; > } > > -- > 2.7.0.rc3 -- 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