Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758010AbZFIHsd (ORCPT ); Tue, 9 Jun 2009 03:48:33 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755626AbZFIHsW (ORCPT ); Tue, 9 Jun 2009 03:48:22 -0400 Received: from yw-out-2324.google.com ([74.125.46.31]:2311 "EHLO yw-out-2324.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757592AbZFIHsS convert rfc822-to-8bit (ORCPT ); Tue, 9 Jun 2009 03:48:18 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=a5xgA9+ZEhQiESASAA4Vzzby9RGK0ozvnmu98FibEDjX4YckHHRx1X4EwjWuega5gl 8aw831/e5Pvn7nbiEtWm3d5soqf9aJsun8cUJQmx8tohO3m6KI+0nBamFutR7iQJ0DM/ EPt27BV4LlCUrrhzGS2dEFTS3+BjuJq3Pq+4s= MIME-Version: 1.0 In-Reply-To: <20090609161925.DD70.A69D9226@jp.fujitsu.com> References: <20090608165457.fa8d17e6.nishimura@mxp.nes.nec.co.jp> <20090609161330.fcd5facb.nishimura@mxp.nes.nec.co.jp> <20090609161925.DD70.A69D9226@jp.fujitsu.com> Date: Tue, 9 Jun 2009 16:48:20 +0900 Message-ID: <28c262360906090048x792fb3f9i6678298b693f6c5a@mail.gmail.com> Subject: Re: [PATCH mmotm] vmscan: handle may_swap more strictly (Re: [PATCH mmotm] vmscan: fix may_swap handling for memcg) From: Minchan Kim To: KOSAKI Motohiro Cc: Daisuke Nishimura , LKML , linux-mm , Andrew Morton , Johannes Weiner , Balbir Singh , KAMEZAWA Hiroyuki Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3985 Lines: 111 Hi, KOSAKI. As you know, this problem caused by if condition(priority) in shrink_zone. Let me have a question. Why do we have to prevent scan value calculation when the priority is zero ? As I know, before split-lru, we didn't do it. Is there any specific issue in case of the priority is zero ? On Tue, Jun 9, 2009 at 4:20 PM, KOSAKI Motohiro wrote: >> > > and, too many recliaming pages is not only memcg issue. I don't think this >> > > patch provide generic solution. >> > > >> > Ah, you're right. It's not only memcg issue. >> > >> How about this one ? >> >> === >> From: Daisuke Nishimura >> >> Commit 2e2e425989080cc534fc0fca154cae515f971cf5 ("vmscan,memcg: reintroduce >> sc->may_swap) add may_swap flag and handle it at get_scan_ratio(). >> >> But the result of get_scan_ratio() is ignored when priority == 0, >> so anon lru is scanned even if may_swap == 0 or nr_swap_pages == 0. >> IMHO, this is not an expected behavior. >> >> As for memcg especially, because of this behavior many and many pages are >> swapped-out just in vain when oom is invoked by mem+swap limit. >> >> This patch is for handling may_swap flag more strictly. >> >> Signed-off-by: Daisuke Nishimura > > Looks great. > your patch doesn't only improve memcg, bug also improve noswap system. > > Thanks. >        Reviewed-by: KOSAKI Motohiro > > > >> --- >>  mm/vmscan.c |   18 +++++++++--------- >>  1 files changed, 9 insertions(+), 9 deletions(-) >> >> diff --git a/mm/vmscan.c b/mm/vmscan.c >> index 2ddcfc8..bacb092 100644 >> --- a/mm/vmscan.c >> +++ b/mm/vmscan.c >> @@ -1407,13 +1407,6 @@ static void get_scan_ratio(struct zone *zone, struct scan_control *sc, >>       unsigned long ap, fp; >>       struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); >> >> -     /* If we have no swap space, do not bother scanning anon pages. */ >> -     if (!sc->may_swap || (nr_swap_pages <= 0)) { >> -             percent[0] = 0; >> -             percent[1] = 100; >> -             return; >> -     } >> - >>       anon  = zone_nr_pages(zone, sc, LRU_ACTIVE_ANON) + >>               zone_nr_pages(zone, sc, LRU_INACTIVE_ANON); >>       file  = zone_nr_pages(zone, sc, LRU_ACTIVE_FILE) + >> @@ -1511,15 +1504,22 @@ static void shrink_zone(int priority, struct zone *zone, >>       enum lru_list l; >>       unsigned long nr_reclaimed = sc->nr_reclaimed; >>       unsigned long swap_cluster_max = sc->swap_cluster_max; >> +     int noswap = 0; >> >> -     get_scan_ratio(zone, sc, percent); >> +     /* If we have no swap space, do not bother scanning anon pages. */ >> +     if (!sc->may_swap || (nr_swap_pages <= 0)) { >> +             noswap = 1; >> +             percent[0] = 0; >> +             percent[1] = 100; >> +     } else >> +             get_scan_ratio(zone, sc, percent); >> >>       for_each_evictable_lru(l) { >>               int file = is_file_lru(l); >>               unsigned long scan; >> >>               scan = zone_nr_pages(zone, sc, l); >> -             if (priority) { >> +             if (priority || noswap) { >>                       scan >>= priority; >>                       scan = (scan * percent[file]) / 100; >>               } > > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at  http://vger.kernel.org/majordomo-info.html > Please read the FAQ at  http://www.tux.org/lkml/ > -- Kinds regards, Minchan Kim -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/