From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with SMTP id 29C316B01F0 for ; Sun, 29 Aug 2010 20:18:48 -0400 (EDT) Received: by iwn33 with SMTP id 33so6135480iwn.14 for ; Sun, 29 Aug 2010 17:18:46 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: <1283096628-4450-1-git-send-email-minchan.kim@gmail.com> <4C7ABD14.9050207@redhat.com> Date: Mon, 30 Aug 2010 09:18:46 +0900 Message-ID: Subject: Re: [PATCH] vmscan: prevent background aging of anon page in no swap system From: Minchan Kim Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org To: Ying Han Cc: Rik van Riel , Andrew Morton , linux-mm , LKML , Venkatesh Pallipadi , KOSAKI Motohiro , Johannes Weiner List-ID: Hi Ying, On Mon, Aug 30, 2010 at 6:23 AM, Ying Han wrote: > On Sun, Aug 29, 2010 at 1:03 PM, Rik van Riel wrote: >> On 08/29/2010 01:45 PM, Ying Han wrote: >> >>> There are few other places in vmscan where we check nr_swap_pages and >>> inactive_anon_is_low. Are we planning to change them to use >>> total_swap_pages >>> to be consistent ? >> >> If that makes sense, maybe the check can just be moved into >> inactive_anon_is_low itself? > > That was the initial patch posted, instead we changed to use > total_swap_pages instead. How this patch looks: > > @@ -1605,6 +1605,9 @@ static int inactive_anon_is_low(struct zone > *zone, struct scan_control *sc) > =A0{ > =A0 =A0 =A0 =A0int low; > > + =A0 =A0 =A0 if (total_swap_pages <=3D 0) > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 return 0; > + > =A0 =A0 =A0 =A0if (scanning_global_lru(sc)) > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0low =3D inactive_anon_is_low_global(zone); > =A0 =A0 =A0 =A0else > @@ -1856,7 +1859,7 @@ static void shrink_zone(int priority, struct zone *= zone, > =A0 =A0 =A0 =A0 * Even if we did not try to evict anon pages at all, we w= ant to > =A0 =A0 =A0 =A0 * rebalance the anon lru active/inactive ratio. > =A0 =A0 =A0 =A0 */ > - =A0 =A0 =A0 if (inactive_anon_is_low(zone, sc) && nr_swap_pages > 0) > + =A0 =A0 =A0 if (inactive_anon_is_low(zone, sc)) > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0shrink_active_list(SWAP_CLUSTER_MAX, zone,= sc, priority, 0); > > =A0 =A0 =A0 =A0throttle_vm_writeout(sc->gfp_mask); > > --Ying > >> I did it intentionally since inactive_anon_is_low have been used both direct reclaim and background path. In this point, your patch could make side effect in swap enabled system when swap is full. I think we need aging in only background if system is swap full. That's because if the swap space is full, we don't reclaim anon pages in direct reclaim path with (nr_swap_pages < 0) and even have been not rebalance it until now. I think direct reclaim path is important about latency as well as reclaim's effectiveness. So if you don't mind, I hope direct reclaim patch would be left just as it = is. --=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