From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail190.messagelabs.com (mail190.messagelabs.com [216.82.249.51]) by kanga.kvack.org (Postfix) with SMTP id BEEB66B003D for ; Fri, 27 Mar 2009 02:30:17 -0400 (EDT) Received: from m1.gw.fujitsu.co.jp ([10.0.50.71]) by fgwmail6.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id n2R6W300001615 for (envelope-from kamezawa.hiroyu@jp.fujitsu.com); Fri, 27 Mar 2009 15:32:03 +0900 Received: from smail (m1 [127.0.0.1]) by outgoing.m1.gw.fujitsu.co.jp (Postfix) with ESMTP id 803CA45DD7A for ; Fri, 27 Mar 2009 15:32:03 +0900 (JST) Received: from s1.gw.fujitsu.co.jp (s1.gw.fujitsu.co.jp [10.0.50.91]) by m1.gw.fujitsu.co.jp (Postfix) with ESMTP id 4EA5E45DD77 for ; Fri, 27 Mar 2009 15:32:03 +0900 (JST) Received: from s1.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s1.gw.fujitsu.co.jp (Postfix) with ESMTP id 424D21DB801B for ; Fri, 27 Mar 2009 15:32:03 +0900 (JST) Received: from m105.s.css.fujitsu.com (m105.s.css.fujitsu.com [10.249.87.105]) by s1.gw.fujitsu.co.jp (Postfix) with ESMTP id CF1621DB8015 for ; Fri, 27 Mar 2009 15:32:02 +0900 (JST) Date: Fri, 27 Mar 2009 15:30:35 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [PATCH] vmscan: memcg needs may_swap (Re: [patch] vmscan: rename sc.may_swap to may_unmap) Message-Id: <20090327153035.35498303.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20090327151926.f252fba7.nishimura@mxp.nes.nec.co.jp> References: <20090206122129.79CC.KOSAKI.MOTOHIRO@jp.fujitsu.com> <20090206044907.GA18467@cmpxchg.org> <20090206135302.628E.KOSAKI.MOTOHIRO@jp.fujitsu.com> <20090206122417.GB1580@cmpxchg.org> <28c262360902060535g22facdd0tf082ca0abaec3f80@mail.gmail.com> <28c262360902060915u18b2fb54t5f2c1f44d03306e3@mail.gmail.com> <20090209194309.GA8491@cmpxchg.org> <20090327151926.f252fba7.nishimura@mxp.nes.nec.co.jp> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Daisuke Nishimura Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Johannes Weiner , MinChan Kim , KOSAKI Motohiro , Andrew Morton , "Rafael J. Wysocki" , Rik van Riel , Balbir Singh List-ID: On Fri, 27 Mar 2009 15:19:26 +0900 Daisuke Nishimura wrote: > Added > Cc: KAMEZAWA Hiroyuki > Cc: Balbir Singh > > I'm sorry for replying to a very old mail. > > > @@ -1713,7 +1713,7 @@ unsigned long try_to_free_mem_cgroup_pag > > { > > struct scan_control sc = { > > .may_writepage = !laptop_mode, > > - .may_swap = 1, > > + .may_unmap = 1, > > .swap_cluster_max = SWAP_CLUSTER_MAX, > > .swappiness = swappiness, > > .order = 0, > > @@ -1723,7 +1723,7 @@ unsigned long try_to_free_mem_cgroup_pag > > struct zonelist *zonelist; > > > > if (noswap) > > - sc.may_swap = 0; > > + sc.may_unmap = 0; > > > > sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | > > (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK); > IIUC, memcg had used may_swap as a flag for "we need to use swap?" as the name indicate. > > Because, when mem+swap hits the limit, trying to swapout pages is meaningless > as it doesn't change mem+swap usage. > Good catch...sigh, I missed this disussion. > What do you think of this patch? > === > From: Daisuke Nishimura > > vmscan-rename-scmay_swap-to-may_unmap.patch removed may_swap flag, > but memcg had used it as a flag for "we need to use swap?", as the > name indicate. > > And in current implementation, memcg cannot reclaim mapped file caches > when mem+swap hits the limit. > When mem+swap hits the limit, swap-out anonymous page doesn't reduce the amount of usage of mem+swap, so, swap-out should be avoided. > re-introduce may_swap flag and handle it at shrink_page_list. > > This patch doesn't influence any scan_control users other than memcg. > > Signed-off-by: Daisuke Nishimura Seems good, Reviewed-by: KAMEZAWA Hiroyuki But hum....Maybe this lru scan work in the same way as the case of !total_swap_pages. (means don't scan anon LRU.) revisit this later. -Kame > --- > mm/vmscan.c | 15 ++++++++++++++- > 1 files changed, 14 insertions(+), 1 deletions(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index c815653..86118d9 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -64,6 +64,9 @@ struct scan_control { > /* Can mapped pages be reclaimed? */ > int may_unmap; > > + /* Can pages be swapped as part of reclaim? */ > + int may_swap; > + > /* This context's SWAP_CLUSTER_MAX. If freeing memory for > * suspend, we effectively ignore SWAP_CLUSTER_MAX. > * In this context, it doesn't matter that we scan the > @@ -616,6 +619,11 @@ static unsigned long shrink_page_list(struct list_head *page_list, > if (!sc->may_unmap && page_mapped(page)) > goto keep_locked; > > + if (!sc->may_swap && PageSwapBacked(page) > + /* SwapCache uses 'swap' already */ > + && !PageSwapCache(page)) > + goto keep_locked; > + > /* Double the slab pressure for mapped and swapcache pages */ > if (page_mapped(page) || PageSwapCache(page)) > sc->nr_scanned++; > @@ -1696,6 +1704,7 @@ unsigned long try_to_free_pages(struct zonelist *zonelist, int order, > .may_writepage = !laptop_mode, > .swap_cluster_max = SWAP_CLUSTER_MAX, > .may_unmap = 1, > + .may_swap = 1, > .swappiness = vm_swappiness, > .order = order, > .mem_cgroup = NULL, > @@ -1715,6 +1724,7 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont, > struct scan_control sc = { > .may_writepage = !laptop_mode, > .may_unmap = 1, > + .may_swap = 1, > .swap_cluster_max = SWAP_CLUSTER_MAX, > .swappiness = swappiness, > .order = 0, > @@ -1724,7 +1734,7 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont, > struct zonelist *zonelist; > > if (noswap) > - sc.may_unmap = 0; > + sc.may_swap = 0; > > sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | > (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK); > @@ -1764,6 +1774,7 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order) > struct scan_control sc = { > .gfp_mask = GFP_KERNEL, > .may_unmap = 1, > + .may_swap = 1, > .swap_cluster_max = SWAP_CLUSTER_MAX, > .swappiness = vm_swappiness, > .order = order, > @@ -2110,6 +2121,7 @@ unsigned long shrink_all_memory(unsigned long nr_pages) > struct scan_control sc = { > .gfp_mask = GFP_KERNEL, > .may_unmap = 0, > + .may_swap = 1, > .may_writepage = 1, > .isolate_pages = isolate_pages_global, > }; > @@ -2292,6 +2304,7 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) > struct scan_control sc = { > .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE), > .may_unmap = !!(zone_reclaim_mode & RECLAIM_SWAP), > + .may_swap = 1, > .swap_cluster_max = max_t(unsigned long, nr_pages, > SWAP_CLUSTER_MAX), > .gfp_mask = gfp_mask, > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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