From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752149Ab0KWHV6 (ORCPT ); Tue, 23 Nov 2010 02:21:58 -0500 Received: from fgwmail6.fujitsu.co.jp ([192.51.44.36]:49779 "EHLO fgwmail6.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752009Ab0KWHV5 (ORCPT ); Tue, 23 Nov 2010 02:21:57 -0500 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 From: KOSAKI Motohiro To: Nick Piggin Subject: Re: [patch] mm: vmscan implement per-zone shrinkers Cc: kosaki.motohiro@jp.fujitsu.com, Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Linus Torvalds In-Reply-To: <20101116074717.GB3460@amd> References: <20101115092452.BEF1.A69D9226@jp.fujitsu.com> <20101116074717.GB3460@amd> Message-Id: <20101123162027.7BB0.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Mailer: Becky! ver. 2.50.07 [ja] Date: Tue, 23 Nov 2010 16:21:54 +0900 (JST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Sorry for the delay. Recently I have no time at all ;) > 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. I'm not worry about so much "0% page cache reclaimable globally" case because I doubt it can be happen in real. > > 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? OK!