From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with SMTP id AE8886B004D for ; Wed, 19 Aug 2009 08:25:49 -0400 (EDT) Received: by yxe14 with SMTP id 14so5630979yxe.12 for ; Wed, 19 Aug 2009 05:25:57 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20090819121017.GA8226@localhost> References: <20090816051502.GB13740@localhost> <20090816112910.GA3208@localhost> <20090818234310.A64B.A69D9226@jp.fujitsu.com> <20090819120117.GB7306@localhost> <2f11576a0908190505h6da96280xf67c962aa3f5ba07@mail.gmail.com> <20090819121017.GA8226@localhost> Date: Wed, 19 Aug 2009 21:25:56 +0900 Message-ID: <28c262360908190525i6e56ead0mb8dcb01c3d1a69f1@mail.gmail.com> Subject: Re: [RFC] respect the referenced bit of KVM guest pages? From: Minchan Kim Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org To: Wu Fengguang Cc: KOSAKI Motohiro , Rik van Riel , Jeff Dike , Avi Kivity , Andrea Arcangeli , "Yu, Wilfred" , "Kleen, Andi" , Hugh Dickins , Andrew Morton , Christoph Lameter , Mel Gorman , LKML , linux-mm List-ID: On Wed, Aug 19, 2009 at 9:10 PM, Wu Fengguang wrote= : > On Wed, Aug 19, 2009 at 08:05:19PM +0800, KOSAKI Motohiro wrote: >> >> page_referenced_file? >> >> I think we should change page_referenced(). >> > >> > Yeah, good catch. >> > >> >> >> >> Instead, How about this? >> >> =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 >> >> >> >> Subject: [PATCH] mm: stop circulating of referenced mlocked pages >> >> >> >> Currently, mlock() systemcall doesn't gurantee to mark the page PG_Ml= ocked >> > >> > =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 =C2=A0 =C2=A0 =C2=A0mark PG_mlocked >> > >> >> because some race prevent page grabbing. >> >> In that case, instead vmscan move the page to unevictable lru. >> >> >> >> However, Recently Wu Fengguang pointed out current vmscan logic isn't= so >> >> efficient. >> >> mlocked page can move circulatly active and inactive list because >> >> vmscan check the page is referenced _before_ cull mlocked page. >> >> >> >> Plus, vmscan should mark PG_Mlocked when cull mlocked 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 PG_mlocked >> > >> >> Otherwise vm stastics show strange number. >> >> >> >> This patch does that. >> > >> > Reviewed-by: Wu Fengguang >> >> Thanks. >> >> >> >> >> Index: b/mm/rmap.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 >> >> --- a/mm/rmap.c =C2=A0 =C2=A0 =C2=A0 2009-08-18 19:48:14.000000000 +0= 900 >> >> +++ b/mm/rmap.c =C2=A0 =C2=A0 =C2=A0 2009-08-18 23:47:34.000000000 +0= 900 >> >> @@ -362,7 +362,9 @@ static int page_referenced_one(struct pa >> >> =C2=A0 =C2=A0 =C2=A0 =C2=A0* unevictable list. >> >> =C2=A0 =C2=A0 =C2=A0 =C2=A0*/ >> >> =C2=A0 =C2=A0 =C2=A0 if (vma->vm_flags & VM_LOCKED) { >> >> - =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 *mapcount =3D 1; =C2=A0/*= break early from loop */ >> >> + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 *mapcount =3D 1; =C2=A0 = =C2=A0 =C2=A0 =C2=A0 =C2=A0/* break early from loop */ >> >> + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 *vm_flags |=3D VM_LOCKED;= /* for prevent to move active list */ >> > >> >> + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 try_set_page_mlocked(vma,= page); >> > >> > That call is not absolutely necessary? >> >> Why? I haven't catch your point. > > Because we'll eventually hit another try_set_page_mlocked() when > trying to unmap the page. Ie. duplicated with another call you added > in this patch. Yes. we don't have to call it and we can make patch simple. I already sent patch on yesterday. http://marc.info/?l=3Dlinux-mm&m=3D125059325722370&w=3D2 I think It's more simple than KOSAKI's idea. Is any problem in my patch ? > > Thanks, > Fengguang > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@kvack.org. =C2=A0For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: email@kvack.org > --=20 Kind 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