Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751493Ab1D1Bty (ORCPT ); Wed, 27 Apr 2011 21:49:54 -0400 Received: from TYO201.gate.nec.co.jp ([202.32.8.193]:39166 "EHLO tyo201.gate.nec.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750779Ab1D1Btw (ORCPT ); Wed, 27 Apr 2011 21:49:52 -0400 Date: Thu, 28 Apr 2011 10:37:05 +0900 From: Daisuke Nishimura To: KAMEZAWA Hiroyuki Cc: Ying Han , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "akpm@linux-foundation.org" , "balbir@linux.vnet.ibm.com" , Daisuke Nishimura Subject: Re: [PATCHv3] memcg: reclaim memory from node in round-robin Message-Id: <20110428103705.a284df87.nishimura@mxp.nes.nec.co.jp> In-Reply-To: <20110428093513.5a6970c0.kamezawa.hiroyu@jp.fujitsu.com> References: <20110427165120.a60c6609.kamezawa.hiroyu@jp.fujitsu.com> <20110428093513.5a6970c0.kamezawa.hiroyu@jp.fujitsu.com> Organization: NEC Soft, Ltd. X-Mailer: Sylpheed 3.1.0 (GTK+ 2.10.14; i686-pc-mingw32) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 8018 Lines: 237 On Thu, 28 Apr 2011 09:35:13 +0900 KAMEZAWA Hiroyuki wrote: > Now, memory cgroup's direct reclaim frees memory from the current node. > But this has some troubles. In usual, when a set of threads works in > cooperative way, they are tend to on the same node. So, if they hit > limits under memcg, it will reclaim memory from themselves, it may be > active working set. > > For example, assume 2 node system which has Node 0 and Node 1 > and a memcg which has 1G limit. After some work, file cacne remains and ^^^^^ cache > and usages are > Node 0: 1M > Node 1: 998M. > > and run an application on Node 0, it will eats its foot before freeing > unnecessary file caches. > > This patch adds round-robin for NUMA and adds equal pressure to each > node. With using cpuset's spread memory feature, this will work very well. > > But yes, better algorithm is appreciated. > > From: Ying Han > Signed-off-by: Ying Han > Signed-off-by: KAMEZAWA Hiroyuki > > Changelog v2->v3 > - added comments for why we need sanity check. > > Changelog v1->v2: > - fixed comments. > - added a logic to avoid scanning unused node. > > --- > include/linux/memcontrol.h | 1 > mm/memcontrol.c | 102 ++++++++++++++++++++++++++++++++++++++++++--- > mm/vmscan.c | 9 +++ > 3 files changed, 105 insertions(+), 7 deletions(-) > > Index: memcg/include/linux/memcontrol.h > =================================================================== > --- memcg.orig/include/linux/memcontrol.h > +++ memcg/include/linux/memcontrol.h > @@ -108,6 +108,7 @@ extern void mem_cgroup_end_migration(str > */ > int mem_cgroup_inactive_anon_is_low(struct mem_cgroup *memcg); > int mem_cgroup_inactive_file_is_low(struct mem_cgroup *memcg); > +int mem_cgroup_select_victim_node(struct mem_cgroup *memcg); > unsigned long mem_cgroup_zone_nr_pages(struct mem_cgroup *memcg, > struct zone *zone, > enum lru_list lru); > Index: memcg/mm/memcontrol.c > =================================================================== > --- memcg.orig/mm/memcontrol.c > +++ memcg/mm/memcontrol.c > @@ -237,6 +237,11 @@ struct mem_cgroup { > * reclaimed from. > */ > int last_scanned_child; > + int last_scanned_node; > +#if MAX_NUMNODES > 1 > + nodemask_t scan_nodes; > + unsigned long next_scan_node_update; > +#endif > /* > * Should the accounting and control be hierarchical, per subtree? > */ > @@ -650,18 +655,27 @@ static void mem_cgroup_soft_scan(struct > this_cpu_add(mem->stat->events[MEM_CGROUP_EVENTS_SOFT_SCAN], val); > } > > +static unsigned long > +mem_cgroup_get_zonestat_node(struct mem_cgroup *mem, int nid, enum lru_list idx) > +{ > + struct mem_cgroup_per_zone *mz; > + u64 total; > + int zid; > + > + for (zid = 0; zid < MAX_NR_ZONES; zid++) { > + mz = mem_cgroup_zoneinfo(mem, nid, zid); > + total += MEM_CGROUP_ZSTAT(mz, idx); > + } > + return total; > +} > static unsigned long mem_cgroup_get_local_zonestat(struct mem_cgroup *mem, > enum lru_list idx) > { > - int nid, zid; > - struct mem_cgroup_per_zone *mz; > + int nid; > u64 total = 0; > > for_each_online_node(nid) > - for (zid = 0; zid < MAX_NR_ZONES; zid++) { > - mz = mem_cgroup_zoneinfo(mem, nid, zid); > - total += MEM_CGROUP_ZSTAT(mz, idx); > - } > + total += mem_cgroup_get_zonestat_node(mem, nid, idx); > return total; > } > > @@ -1471,6 +1485,81 @@ mem_cgroup_select_victim(struct mem_cgro > return ret; > } > > +#if MAX_NUMNODES > 1 > + > +/* > + * Update nodemask always is not very good. Even if we have empty > + * list, or wrong list here, we can start from some node and traverse all nodes > + * based on zonelist. So, update the list loosely once in 10 secs. > + * > + */ > +static void mem_cgroup_may_update_nodemask(struct mem_cgroup *mem) > +{ > + int nid; > + > + if (time_after(mem->next_scan_node_update, jiffies)) > + return; > + Shouldn't it be time_before() or time_after(jiffies, next_scan_node_update) ? Looks good to me, otherwise. Thanks, Daisuke Nishimura. > + mem->next_scan_node_update = jiffies + 10*HZ; > + /* make a nodemask where this memcg uses memory from */ > + mem->scan_nodes = node_states[N_HIGH_MEMORY]; > + > + for_each_node_mask(nid, node_states[N_HIGH_MEMORY]) { > + > + if (mem_cgroup_get_zonestat_node(mem, nid, LRU_INACTIVE_FILE) || > + mem_cgroup_get_zonestat_node(mem, nid, LRU_ACTIVE_FILE)) > + continue; > + > + if (total_swap_pages && > + (mem_cgroup_get_zonestat_node(mem, nid, LRU_INACTIVE_ANON) || > + mem_cgroup_get_zonestat_node(mem, nid, LRU_ACTIVE_ANON))) > + continue; > + node_clear(nid, mem->scan_nodes); > + } > +} > + > +/* > + * Selecting a node where we start reclaim from. Because what we need is just > + * reducing usage counter, start from anywhere is O,K. Considering > + * memory reclaim from current node, there are pros. and cons. > + * > + * Freeing memory from current node means freeing memory from a node which > + * we'll use or we've used. So, it may make LRU bad. And if several threads > + * hit limits, it will see a contention on a node. But freeing from remote > + * node means more costs for memory reclaim because of memory latency. > + * > + * Now, we use round-robin. Better algorithm is welcomed. > + */ > +int mem_cgroup_select_victim_node(struct mem_cgroup *mem) > +{ > + int node; > + > + mem_cgroup_may_update_nodemask(mem); > + node = mem->last_scanned_node; > + > + node = next_node(node, mem->scan_nodes); > + if (node == MAX_NUMNODES) > + node = first_node(mem->scan_nodes); > + /* > + * We call this when we hit limit, not when pages are added to LRU. > + * No LRU may hold pages because all pages are UNEVICTABLE or > + * memcg is too small and all pages are not on LRU. In that case, > + * we use curret node. > + */ > + if (unlikely(node == MAX_NUMNODES)) > + node = numa_node_id(); > + > + mem->last_scanned_node = node; > + return node; > +} > + > +#else > +int mem_cgroup_select_victim_node(struct mem_cgroup *mem) > +{ > + return 0; > +} > +#endif > + > /* > * Scan the hierarchy if needed to reclaim memory. We remember the last child > * we reclaimed from, so that we don't end up penalizing one child extensively > @@ -4678,6 +4767,7 @@ mem_cgroup_create(struct cgroup_subsys * > res_counter_init(&mem->memsw, NULL); > } > mem->last_scanned_child = 0; > + mem->last_scanned_node = MAX_NUMNODES; > INIT_LIST_HEAD(&mem->oom_notify); > > if (parent) > Index: memcg/mm/vmscan.c > =================================================================== > --- memcg.orig/mm/vmscan.c > +++ memcg/mm/vmscan.c > @@ -2198,6 +2198,7 @@ unsigned long try_to_free_mem_cgroup_pag > { > struct zonelist *zonelist; > unsigned long nr_reclaimed; > + int nid; > struct scan_control sc = { > .may_writepage = !laptop_mode, > .may_unmap = 1, > @@ -2208,10 +2209,16 @@ unsigned long try_to_free_mem_cgroup_pag > .mem_cgroup = mem_cont, > .nodemask = NULL, /* we don't care the placement */ > }; > + /* > + * Unlike direct reclaim via alloc_pages(), memcg's reclaim > + * don't take care of from where we get pages . So, the node where > + * we start scan is not needed to be current node. > + */ > + nid = mem_cgroup_select_victim_node(mem_cont); > > sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | > (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK); > - zonelist = NODE_DATA(numa_node_id())->node_zonelists; > + zonelist = NODE_DATA(nid)->node_zonelists; > > trace_mm_vmscan_memcg_reclaim_begin(0, > sc.may_writepage, > -- 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/