From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx187.postini.com [74.125.245.187]) by kanga.kvack.org (Postfix) with SMTP id 63E836B004A for ; Tue, 10 Apr 2012 11:16:21 -0400 (EDT) Received: by vcbfk14 with SMTP id fk14so3657802vcb.14 for ; Tue, 10 Apr 2012 08:16:20 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: <1334000524-23972-1-git-send-email-yinghan@google.com> Date: Tue, 10 Apr 2012 23:16:19 +0800 Message-ID: Subject: Re: [PATCH] Revert "mm: vmscan: fix misused nr_reclaimed in shrink_mem_cgroup_zone()" From: Hillf Danton Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org List-ID: To: Ying Han Cc: Andrew Morton , Rik van Riel , Hugh Dickins , linux-mm@kvack.org, LKML add lkml On Tue, Apr 10, 2012 at 11:00 PM, Hillf Danton wrote: > On Tue, Apr 10, 2012 at 3:42 AM, Ying Han wrote: >> This reverts commit c38446cc65e1f2b3eb8630c53943b94c4f65f670. >> >> Before the commit, the code makes senses to me but not after the commit.= The >> "nr_reclaimed" is the number of pages reclaimed by scanning through the = memcg's >> lru lists. The "nr_to_reclaim" is the target value for the whole functio= n. For >> example, we like to early break the reclaim if reclaimed 32 pages under = direct >> reclaim (not DEF_PRIORITY). >> >> After the reverted commit, the target "nr_to_reclaim" is decremented eac= h time >> by "nr_reclaimed" but we still use it to compare the "nr_reclaimed". It = just >> doesn't make sense to me... >> > I downloaded mm/vmscan.c from the next tree a couple minutes ago, and > see > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0.nr_to_reclaim =3D= SWAP_CLUSTER_MAX, > and > =C2=A0 =C2=A0 =C2=A0 =C2=A0nr_reclaimed =3D do_try_to_free_pages(zonelist= , &sc, &shrink); > > in try_to_free_pages(). > > I also see > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0total_scanned +=3D= sc->nr_scanned; > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0if (sc->nr_reclaim= ed >=3D sc->nr_to_reclaim) > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2= =A0 =C2=A0goto out; > > in do_try_to_free_pages(), > > then would you please say a few words about the sense > of the check of nr_to_reclaim? > > >> Signed-off-by: Ying Han >> --- >> =C2=A0mm/vmscan.c | =C2=A0 =C2=A07 +------ >> =C2=A01 files changed, 1 insertions(+), 6 deletions(-) >> >> diff --git a/mm/vmscan.c b/mm/vmscan.c >> index 33c332b..1a51868 100644 >> --- a/mm/vmscan.c >> +++ b/mm/vmscan.c >> @@ -2107,12 +2107,7 @@ restart: >> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 * with multiple = processes reclaiming pages, the total >> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 * freeing target= can get unreasonably large. >> =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 (nr_reclaimed >=3D= nr_to_reclaim) >> - =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 = =C2=A0 nr_to_reclaim =3D 0; >> - =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 else >> - =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 = =C2=A0 nr_to_reclaim -=3D nr_reclaimed; >> - >> - =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 if (!nr_to_reclaim &&= priority < DEF_PRIORITY) >> + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 if (nr_reclaimed >=3D= nr_to_reclaim && priority < DEF_PRIORITY) >> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 = =C2=A0 =C2=A0break; >> =C2=A0 =C2=A0 =C2=A0 =C2=A0} >> =C2=A0 =C2=A0 =C2=A0 =C2=A0blk_finish_plug(&plug); >> -- >> 1.7.7.3 >> -- 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