Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751495AbZDAELt (ORCPT ); Wed, 1 Apr 2009 00:11:49 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750777AbZDAELj (ORCPT ); Wed, 1 Apr 2009 00:11:39 -0400 Received: from cmpxchg.org ([85.214.51.133]:60626 "EHLO cmpxchg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750757AbZDAELi (ORCPT ); Wed, 1 Apr 2009 00:11:38 -0400 Date: Wed, 1 Apr 2009 06:09:51 +0200 From: Johannes Weiner To: KOSAKI Motohiro Cc: KAMEZAWA Hiroyuki , Minchan Kim , Daisuke Nishimura , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , "Rafael J. Wysocki" , Rik van Riel , Balbir Singh Subject: Re: [PATCH] vmscan: memcg needs may_swap (Re: [patch] vmscan: rename sc.may_swap to may_unmap) Message-ID: <20090401040951.GA1548@cmpxchg.org> References: <28c262360903301826w6429720es8ceb361cfc088b1@mail.gmail.com> <20090331104237.e689f279.kamezawa.hiroyu@jp.fujitsu.com> <20090331104625.B1C7.A69D9226@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090331104625.B1C7.A69D9226@jp.fujitsu.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1761 Lines: 50 On Tue, Mar 31, 2009 at 10:48:32AM +0900, KOSAKI Motohiro wrote: > > > Sorry for too late response. > > > I don't know memcg well. > > > > > > The memcg managed to use may_swap well with global page reclaim until now. > > > I think that was because may_swap can represent both meaning. > > > Do we need each variables really ? > > > > > > How about using union variable ? > > > > or Just removing one of them ? > > I hope all may_unmap user convert to using may_swap. > may_swap is more efficient and cleaner meaning. How about making may_swap mean the following: @@ -642,6 +639,8 @@ static unsigned long shrink_page_list(st * Try to allocate it some swap space here. */ if (PageAnon(page) && !PageSwapCache(page)) { + if (!sc->map_swap) + goto keep_locked; if (!(sc->gfp_mask & __GFP_IO)) goto keep_locked; if (!add_to_swap(page)) try_to_free_pages() always sets it. try_to_free_mem_cgroup_pages() sets it depending on whether it really wants swapping, and only swapping, right? But the above would still reclaim already swapped anon pages and I don't know the memory controller. balance_pgdat() always sets it. __zone_reclaim() sets it depending on zone_reclaim_mode. The RECLAIM_SWAP bit of this field and its documentation in Documentation/sysctl/vm.txt suggests it also really only means swap. shrink_all_memory() would be the sole user of may_unmap because it really wants to eat cache first. But this could be figured out on a different occasion. Hannes -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/