From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with SMTP id C83928D0080 for ; Tue, 16 Nov 2010 02:47:20 -0500 (EST) Date: Tue, 16 Nov 2010 18:47:17 +1100 From: Nick Piggin Subject: Re: [patch] mm: vmscan implement per-zone shrinkers Message-ID: <20101116074717.GB3460@amd> References: <20101109123246.GA11477@amd> <20101114182614.BEE5.A69D9226@jp.fujitsu.com> <20101115092452.BEF1.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20101115092452.BEF1.A69D9226@jp.fujitsu.com> Sender: owner-linux-mm@kvack.org To: KOSAKI Motohiro Cc: Nick Piggin , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Linus Torvalds List-ID: On Mon, Nov 15, 2010 at 09:50:36AM +0900, KOSAKI Motohiro wrote: > > > @@ -1835,8 +1978,6 @@ static void shrink_zone(int priority, st > > > break; > > > } > > > > > > - sc->nr_reclaimed = nr_reclaimed; > > > - > > > /* > > > * Even if we did not try to evict anon pages at all, we want to > > > * rebalance the anon lru active/inactive ratio. > > > @@ -1844,6 +1985,23 @@ static void shrink_zone(int priority, st > > > if (inactive_anon_is_low(zone, sc)) > > > shrink_active_list(SWAP_CLUSTER_MAX, zone, sc, priority, 0); > > > > > > + /* > > > + * Don't shrink slabs when reclaiming memory from > > > + * over limit cgroups > > > + */ > > > + if (sc->may_reclaim_slab) { > > > + struct reclaim_state *reclaim_state = current->reclaim_state; > > > + > > > + shrink_slab(zone, sc->nr_scanned - nr_scanned, > > > > Doubtful calculation. What mean "sc->nr_scanned - nr_scanned"? > > I think nr_scanned simply keep old slab balancing behavior. > > And per-zone reclaim can lead to new issue. On 32bit highmem system, > theorically the system has following memory usage. > > ZONE_HIGHMEM: 100% used for page cache > ZONE_NORMAL: 100% used for slab > > So, traditional page-cache/slab balancing may not work. I think following Yes, in theory you are right. I guess in theory the same hole exists if we have 0% page cache reclaimable globally, but this may be slightly more likely to hit. > new calculation or somethinhg else is necessary. > > if (zone_reclaimable_pages() > NR_SLAB_RECLAIMABLE) { > using current calculation > } else { > shrink number of "objects >> reclaim-priority" objects > (as page cache scanning calculation) > } > > However, it can be separate this patch, perhaps. I agree. In fact, perhaps the new calculation would work well in all cases anyway, so maybe we should move away from making slab reclaim a slave to pagecache reclaim. Can we approach that in subsequent patches? Thanks, Nick -- 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 policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: email@kvack.org