From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with SMTP id 7FB406B004D for ; Thu, 11 Jun 2009 05:36:32 -0400 (EDT) Received: by yw-out-1718.google.com with SMTP id 5so664567ywm.26 for ; Thu, 11 Jun 2009 02:37:41 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20090611173819.0f76e431.kamezawa.hiroyu@jp.fujitsu.com> References: <20090611165535.cf46bf29.kamezawa.hiroyu@jp.fujitsu.com> <20090611170152.7a43b13b.kamezawa.hiroyu@jp.fujitsu.com> <20090611172249.6D3C.A69D9226@jp.fujitsu.com> <20090611173819.0f76e431.kamezawa.hiroyu@jp.fujitsu.com> Date: Thu, 11 Jun 2009 18:37:40 +0900 Message-ID: <28c262360906110237u1f3d1877hae54a51575955549@mail.gmail.com> Subject: Re: [PATCH 2/3] check unevictable flag in lumy reclaim v2 From: Minchan Kim Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org To: KAMEZAWA Hiroyuki Cc: KOSAKI Motohiro , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "nishimura@mxp.nes.nec.co.jp" , "balbir@linux.vnet.ibm.com" , "akpm@linux-foundation.org" , apw@canonical.com, riel@redhat.com, mel@csn.ul.ie List-ID: On Thu, Jun 11, 2009 at 5:38 PM, KAMEZAWA Hiroyuki wrote: > How about this ? > > From: KAMEZAWA Hiroyuki > > Lumpy reclaim check pages from their pfn. Then, it can find unevictable p= ages > in its loop. > Abort lumpy reclaim when we find Unevictable page, we never get a lump > of pages for requested order. > > Changelog: v1->v2 > =C2=A0- rewrote commet. > > Signed-off-by: KAMEZAWA Hiroyuki > --- > =C2=A0mm/vmscan.c | =C2=A0 =C2=A09 +++++++++ > =C2=A01 file changed, 9 insertions(+) > > Index: lumpy-reclaim-trial/mm/vmscan.c > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > --- lumpy-reclaim-trial.orig/mm/vmscan.c > +++ lumpy-reclaim-trial/mm/vmscan.c > @@ -936,6 +936,15 @@ static unsigned long isolate_lru_pages(u > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2= =A0 =C2=A0/* Check that we have not crossed a zone boundary. */ > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2= =A0 =C2=A0if (unlikely(page_zone_id(cursor_page) !=3D zone_id)) > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2= =A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0continue; > + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 = =C2=A0 /* > + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 = =C2=A0 =C2=A0* We tries to free all pages in this range to create > + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 = =C2=A0 =C2=A0* a free large page. Then, if the range includes a page > + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 = =C2=A0 =C2=A0* never be reclaimed, we have no reason to do more. > + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 = =C2=A0 =C2=A0* PageUnevictable page is not a page which can be > + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 = =C2=A0 =C2=A0* easily freed. Abort this scan now. > + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 = =C2=A0 =C2=A0*/ > + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 = =C2=A0 if (unlikely(PageUnevictable(cursor_page))) > + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 = =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 break; __isolate_lru_pages already checked PageUnevictable to return error. I want to remove repeated check although it is trivial. By your patch, It seems to remove PageUnevictable check in __isolate_lru_pa= ges. But I know that. If we remove PageUnevictable check in __isolate_lru_pages, it can't go into BUG in non-lumpy case. ( I mentioned following as code) case -EBUSY: /* else it is being freed elsewhere */ list_move(&page->lru, src); continue; default: BUG(); } It means we can remove BUG in non-lumpy case and then add BUG into __isolate_lru_pages directly. If we can do it, we can remove unnecessary PageUnevictable check in __isolate_lru_page. I am not sure this is right in case of memcg. --=20 Kinds regards, Minchan Kim -- 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