On Wed, Apr 13, 2011 at 1:58 AM, KAMEZAWA Hiroyuki < kamezawa.hiroyu@jp.fujitsu.com> wrote: > On Wed, 13 Apr 2011 00:03:05 -0700 > Ying Han wrote: > > > This is the main loop of per-memcg background reclaim which is > implemented in > > function balance_mem_cgroup_pgdat(). > > > > The function performs a priority loop similar to global reclaim. During > each > > iteration it invokes balance_pgdat_node() for all nodes on the system, > which > > is another new function performs background reclaim per node. A fairness > > mechanism is implemented to remember the last node it was reclaiming from > and > > always start at the next one. After reclaiming each node, it checks > > mem_cgroup_watermark_ok() and breaks the priority loop if it returns > true. The > > per-memcg zone will be marked as "unreclaimable" if the scanning rate is > much > > greater than the reclaiming rate on the per-memcg LRU. The bit is cleared > when > > there is a page charged to the memcg being freed. Kswapd breaks the > priority > > loop if all the zones are marked as "unreclaimable". > > > > Hmm, bigger than expected. I'm glad if you can divide this into small > pieces. > see below. > > > > changelog v3..v2: > > 1. change mz->all_unreclaimable to be boolean. > > 2. define ZONE_RECLAIMABLE_RATE macro shared by zone and per-memcg > reclaim. > > 3. some more clean-up. > > > > changelog v2..v1: > > 1. move the per-memcg per-zone clear_unreclaimable into uncharge stage. > > 2. shared the kswapd_run/kswapd_stop for per-memcg and global background > > reclaim. > > 3. name the per-memcg memcg as "memcg-id" (css->id). And the global > kswapd > > keeps the same name. > > 4. fix a race on kswapd_stop while the per-memcg-per-zone info could be > accessed > > after freeing. > > 5. add the fairness in zonelist where memcg remember the last zone > reclaimed > > from. > > > > Signed-off-by: Ying Han > > --- > > include/linux/memcontrol.h | 33 +++++++ > > include/linux/swap.h | 2 + > > mm/memcontrol.c | 136 +++++++++++++++++++++++++++++ > > mm/vmscan.c | 208 > ++++++++++++++++++++++++++++++++++++++++++++ > > 4 files changed, 379 insertions(+), 0 deletions(-) > > > > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h > > index f7ffd1f..a8159f5 100644 > > --- a/include/linux/memcontrol.h > > +++ b/include/linux/memcontrol.h > > @@ -88,6 +88,9 @@ extern int mem_cgroup_init_kswapd(struct mem_cgroup > *mem, > > struct kswapd *kswapd_p); > > extern void mem_cgroup_clear_kswapd(struct mem_cgroup *mem); > > extern wait_queue_head_t *mem_cgroup_kswapd_wait(struct mem_cgroup > *mem); > > +extern int mem_cgroup_last_scanned_node(struct mem_cgroup *mem); > > +extern int mem_cgroup_select_victim_node(struct mem_cgroup *mem, > > + const nodemask_t *nodes); > > > > static inline > > int mm_match_cgroup(const struct mm_struct *mm, const struct mem_cgroup > *cgroup) > > @@ -152,6 +155,12 @@ static inline void mem_cgroup_dec_page_stat(struct > page *page, > > unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int > order, > > gfp_t gfp_mask); > > u64 mem_cgroup_get_limit(struct mem_cgroup *mem); > > +void mem_cgroup_clear_unreclaimable(struct mem_cgroup *mem, struct page > *page); > > +bool mem_cgroup_zone_reclaimable(struct mem_cgroup *mem, int nid, int > zid); > > +bool mem_cgroup_mz_unreclaimable(struct mem_cgroup *mem, struct zone > *zone); > > +void mem_cgroup_mz_set_unreclaimable(struct mem_cgroup *mem, struct zone > *zone); > > +void mem_cgroup_mz_pages_scanned(struct mem_cgroup *mem, struct zone* > zone, > > + unsigned long nr_scanned); > > > > #ifdef CONFIG_TRANSPARENT_HUGEPAGE > > void mem_cgroup_split_huge_fixup(struct page *head, struct page *tail); > > @@ -342,6 +351,25 @@ static inline void mem_cgroup_dec_page_stat(struct > page *page, > > { > > } > > > > +static inline void mem_cgroup_mz_pages_scanned(struct mem_cgroup *mem, > > + struct zone *zone, > > + unsigned long nr_scanned) > > +{ > > +} > > + > > +static inline void mem_cgroup_clear_unreclaimable(struct page *page, > > + struct zone *zone) > > +{ > > +} > > +static inline void mem_cgroup_mz_set_unreclaimable(struct mem_cgroup > *mem, > > + struct zone *zone) > > +{ > > +} > > +static inline bool mem_cgroup_mz_unreclaimable(struct mem_cgroup *mem, > > + struct zone *zone) > > +{ > > +} > > + > > static inline > > unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int > order, > > gfp_t gfp_mask) > > @@ -360,6 +388,11 @@ static inline void > mem_cgroup_split_huge_fixup(struct page *head, > > { > > } > > > > +static inline bool mem_cgroup_zone_reclaimable(struct mem_cgroup *mem, > int nid, > > + int zid) > > +{ > > + return false; > > +} > > #endif /* CONFIG_CGROUP_MEM_CONT */ > > > > #if !defined(CONFIG_CGROUP_MEM_RES_CTLR) || !defined(CONFIG_DEBUG_VM) > > diff --git a/include/linux/swap.h b/include/linux/swap.h > > index 17e0511..319b800 100644 > > --- a/include/linux/swap.h > > +++ b/include/linux/swap.h > > @@ -160,6 +160,8 @@ enum { > > SWP_SCANNING = (1 << 8), /* refcount in scan_swap_map */ > > }; > > > > +#define ZONE_RECLAIMABLE_RATE 6 > > + > > #define SWAP_CLUSTER_MAX 32 > > #define COMPACT_CLUSTER_MAX SWAP_CLUSTER_MAX > > > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > > index acd84a8..efeade3 100644 > > --- a/mm/memcontrol.c > > +++ b/mm/memcontrol.c > > @@ -133,7 +133,10 @@ struct mem_cgroup_per_zone { > > bool on_tree; > > struct mem_cgroup *mem; /* Back pointer, we cannot > */ > > /* use container_of > */ > > + unsigned long pages_scanned; /* since last reclaim */ > > + bool all_unreclaimable; /* All pages pinned > */ > > }; > > + > > /* Macro for accessing counter */ > > #define MEM_CGROUP_ZSTAT(mz, idx) ((mz)->count[(idx)]) > > > > @@ -275,6 +278,11 @@ struct mem_cgroup { > > > > int wmark_ratio; > > > > + /* While doing per cgroup background reclaim, we cache the > > + * last node we reclaimed from > > + */ > > + int last_scanned_node; > > + > > wait_queue_head_t *kswapd_wait; > > }; > > > > @@ -1129,6 +1137,96 @@ mem_cgroup_get_reclaim_stat_from_page(struct page > *page) > > return &mz->reclaim_stat; > > } > > > > +static unsigned long mem_cgroup_zone_reclaimable_pages( > > + struct mem_cgroup_per_zone *mz) > > +{ > > + int nr; > > + nr = MEM_CGROUP_ZSTAT(mz, LRU_ACTIVE_FILE) + > > + MEM_CGROUP_ZSTAT(mz, LRU_INACTIVE_FILE); > > + > > + if (nr_swap_pages > 0) > > + nr += MEM_CGROUP_ZSTAT(mz, LRU_ACTIVE_ANON) + > > + MEM_CGROUP_ZSTAT(mz, LRU_INACTIVE_ANON); > > + > > + return nr; > > +} > > + > > +void mem_cgroup_mz_pages_scanned(struct mem_cgroup *mem, struct zone* > zone, > > + unsigned long nr_scanned) > > +{ > > + struct mem_cgroup_per_zone *mz = NULL; > > + int nid = zone_to_nid(zone); > > + int zid = zone_idx(zone); > > + > > + if (!mem) > > + return; > > + > > + mz = mem_cgroup_zoneinfo(mem, nid, zid); > > + if (mz) > > + mz->pages_scanned += nr_scanned; > > +} > > + > > +bool mem_cgroup_zone_reclaimable(struct mem_cgroup *mem, int nid, int > zid) > > +{ > > + struct mem_cgroup_per_zone *mz = NULL; > > + > > + if (!mem) > > + return 0; > > + > > + mz = mem_cgroup_zoneinfo(mem, nid, zid); > > + if (mz) > > + return mz->pages_scanned < > > + mem_cgroup_zone_reclaimable_pages(mz) * > > + ZONE_RECLAIMABLE_RATE; > > + return 0; > > +} > > + > > +bool mem_cgroup_mz_unreclaimable(struct mem_cgroup *mem, struct zone > *zone) > > +{ > > + struct mem_cgroup_per_zone *mz = NULL; > > + int nid = zone_to_nid(zone); > > + int zid = zone_idx(zone); > > + > > + if (!mem) > > + return false; > > + > > + mz = mem_cgroup_zoneinfo(mem, nid, zid); > > + if (mz) > > + return mz->all_unreclaimable; > > + > > + return false; > > +} > > + > > +void mem_cgroup_mz_set_unreclaimable(struct mem_cgroup *mem, struct zone > *zone) > > +{ > > + struct mem_cgroup_per_zone *mz = NULL; > > + int nid = zone_to_nid(zone); > > + int zid = zone_idx(zone); > > + > > + if (!mem) > > + return; > > + > > + mz = mem_cgroup_zoneinfo(mem, nid, zid); > > + if (mz) > > + mz->all_unreclaimable = true; > > +} > > + > > +void mem_cgroup_clear_unreclaimable(struct mem_cgroup *mem, struct page > *page) > > +{ > > + struct mem_cgroup_per_zone *mz = NULL; > > + > > + if (!mem) > > + return; > > + > > + mz = page_cgroup_zoneinfo(mem, page); > > + if (mz) { > > + mz->pages_scanned = 0; > > + mz->all_unreclaimable = false; > > + } > > + > > + return; > > +} > > + > > unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan, > > struct list_head *dst, > > unsigned long *scanned, int order, > > @@ -1545,6 +1643,32 @@ static int mem_cgroup_hierarchical_reclaim(struct > mem_cgroup *root_mem, > > } > > > > /* > > + * Visit the first node after the last_scanned_node of @mem and use that > to > > + * reclaim free pages from. > > + */ > > +int > > +mem_cgroup_select_victim_node(struct mem_cgroup *mem, const nodemask_t > *nodes) > > +{ > > + int next_nid; > > + int last_scanned; > > + > > + last_scanned = mem->last_scanned_node; > > + > > + /* Initial stage and start from node0 */ > > + if (last_scanned == -1) > > + next_nid = 0; > > + else > > + next_nid = next_node(last_scanned, *nodes); > > + > > + if (next_nid == MAX_NUMNODES) > > + next_nid = first_node(*nodes); > > + > > + mem->last_scanned_node = next_nid; > > + > > + return next_nid; > > +} > > + > > +/* > > * Check OOM-Killer is already running under our hierarchy. > > * If someone is running, return false. > > */ > > @@ -2779,6 +2903,7 @@ __mem_cgroup_uncharge_common(struct page *page, > enum charge_type ctype) > > * special functions. > > */ > > > > + mem_cgroup_clear_unreclaimable(mem, page); > > Hmm, do we this always at uncharge ? > > I doubt we really need mz->all_unreclaimable .... > > Anyway, I'd like to see this all_unreclaimable logic in an independet > patch. > Because direct-relcaim pass should see this, too. > > So, could you devide this pieces into > > 1. record last node .... I wonder this logic should be used in > direct-reclaim pass, too. > > 2. all_unreclaimable .... direct reclaim will be affected, too. > > 3. scanning core. > Ok. will make the change for the next post. > > > > > unlock_page_cgroup(pc); > > /* > > * even after unlock, we have mem->res.usage here and this memcg > > @@ -4501,6 +4626,8 @@ static int alloc_mem_cgroup_per_zone_info(struct > mem_cgroup *mem, int node) > > mz->usage_in_excess = 0; > > mz->on_tree = false; > > mz->mem = mem; > > + mz->pages_scanned = 0; > > + mz->all_unreclaimable = false; > > } > > return 0; > > } > > @@ -4651,6 +4778,14 @@ wait_queue_head_t *mem_cgroup_kswapd_wait(struct > mem_cgroup *mem) > > return mem->kswapd_wait; > > } > > > > +int mem_cgroup_last_scanned_node(struct mem_cgroup *mem) > > +{ > > + if (!mem) > > + return -1; > > + > > + return mem->last_scanned_node; > > +} > > + > > static int mem_cgroup_soft_limit_tree_init(void) > > { > > struct mem_cgroup_tree_per_node *rtpn; > > @@ -4726,6 +4861,7 @@ mem_cgroup_create(struct cgroup_subsys *ss, struct > cgroup *cont) > > res_counter_init(&mem->memsw, NULL); > > } > > mem->last_scanned_child = 0; > > + mem->last_scanned_node = -1; > > INIT_LIST_HEAD(&mem->oom_notify); > > > > if (parent) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > > index a1a1211..6571eb8 100644 > > --- a/mm/vmscan.c > > +++ b/mm/vmscan.c > > @@ -47,6 +47,8 @@ > > > > #include > > > > +#include > > + > > #include "internal.h" > > > > #define CREATE_TRACE_POINTS > > @@ -111,6 +113,8 @@ struct scan_control { > > * are scanned. > > */ > > nodemask_t *nodemask; > > + > > + int priority; > > }; > > > > #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru)) > > @@ -1410,6 +1414,9 @@ shrink_inactive_list(unsigned long nr_to_scan, > struct zone *zone, > > ISOLATE_BOTH : ISOLATE_INACTIVE, > > zone, sc->mem_cgroup, > > 0, file); > > + > > + mem_cgroup_mz_pages_scanned(sc->mem_cgroup, zone, > nr_scanned); > > + > > /* > > * mem_cgroup_isolate_pages() keeps track of > > * scanned pages on its own. > > @@ -1529,6 +1536,7 @@ static void shrink_active_list(unsigned long > nr_pages, struct zone *zone, > > * mem_cgroup_isolate_pages() keeps track of > > * scanned pages on its own. > > */ > > + mem_cgroup_mz_pages_scanned(sc->mem_cgroup, zone, > pgscanned); > > } > > > > reclaim_stat->recent_scanned[file] += nr_taken; > > @@ -2632,11 +2640,211 @@ static void kswapd_try_to_sleep(struct kswapd > *kswapd_p, int order, > > finish_wait(wait_h, &wait); > > } > > > > +#ifdef CONFIG_CGROUP_MEM_RES_CTLR > > +/* > > + * The function is used for per-memcg LRU. It scanns all the zones of > the > > + * node and returns the nr_scanned and nr_reclaimed. > > + */ > > +static void balance_pgdat_node(pg_data_t *pgdat, int order, > > + struct scan_control *sc) > > +{ > > + int i, end_zone; > > + unsigned long total_scanned; > > + struct mem_cgroup *mem_cont = sc->mem_cgroup; > > + int priority = sc->priority; > > + int nid = pgdat->node_id; > > + > > + /* > > + * Scan in the highmem->dma direction for the highest > > + * zone which needs scanning > > + */ > > + for (i = pgdat->nr_zones - 1; i >= 0; i--) { > > + struct zone *zone = pgdat->node_zones + i; > > + > > + if (!populated_zone(zone)) > > + continue; > > + > > + if (mem_cgroup_mz_unreclaimable(mem_cont, zone) && > > + priority != DEF_PRIORITY) > > + continue; > > + /* > > + * Do some background aging of the anon list, to give > > + * pages a chance to be referenced before reclaiming. > > + */ > > + if (inactive_anon_is_low(zone, sc)) > > + shrink_active_list(SWAP_CLUSTER_MAX, zone, > > + sc, priority, 0); > > + > > + end_zone = i; > > + goto scan; > > + } > > I don't want to see zone balancing logic in memcg. > It should be a work of global lru. > > IOW, even if we remove global LRU finally, we should > implement zone balancing logic in _global_ (per node) kswapd. > (kswapd can pass zone mask to each memcg.) > > If you want some clever logic for memcg specail, I think it should be > deteciting 'which node should be victim' logic rather than round-robin. > (But yes, starting from easy round robin makes sense.) > > So, could you add more simple one ? > > do { > select victim node > do reclaim > } while (need_stop) > > zone balancing should be done other than memcg. > > what we really need to improve is 'select victim node'. > I will separate out the logic in the next post. So it would be easier to optimize each individual functionality. --Ying > > Thanks, > -Kame > > > > + return; > > + > > +scan: > > + total_scanned = 0; > > + /* > > + * Now scan the zone in the dma->highmem direction, stopping > > + * at the last zone which needs scanning. > > + * > > + * We do this because the page allocator works in the opposite > > + * direction. This prevents the page allocator from allocating > > + * pages behind kswapd's direction of progress, which would > > + * cause too much scanning of the lower zones. > > + */ > > + for (i = 0; i <= end_zone; i++) { > > + struct zone *zone = pgdat->node_zones + i; > > + > > + if (!populated_zone(zone)) > > + continue; > > + > > + if (mem_cgroup_mz_unreclaimable(mem_cont, zone) && > > + priority != DEF_PRIORITY) > > + continue; > > + > > + sc->nr_scanned = 0; > > + shrink_zone(priority, zone, sc); > > + total_scanned += sc->nr_scanned; > > + > > + if (mem_cgroup_mz_unreclaimable(mem_cont, zone)) > > + continue; > > + > > + if (!mem_cgroup_zone_reclaimable(mem_cont, nid, i)) > > + mem_cgroup_mz_set_unreclaimable(mem_cont, zone); > > + > > + /* > > + * If we've done a decent amount of scanning and > > + * the reclaim ratio is low, start doing writepage > > + * even in laptop mode > > + */ > > + if (total_scanned > SWAP_CLUSTER_MAX * 2 && > > + total_scanned > sc->nr_reclaimed + sc->nr_reclaimed / > 2) { > > + sc->may_writepage = 1; > > + } > > + } > > + > > + sc->nr_scanned = total_scanned; > > + return; > > +} > > + > > +/* > > + * Per cgroup background reclaim. > > + * TODO: Take off the order since memcg always do order 0 > > + */ > > +static unsigned long balance_mem_cgroup_pgdat(struct mem_cgroup > *mem_cont, > > + int order) > > +{ > > + int i, nid; > > + int start_node; > > + int priority; > > + bool wmark_ok; > > + int loop; > > + pg_data_t *pgdat; > > + nodemask_t do_nodes; > > + unsigned long total_scanned; > > + struct scan_control sc = { > > + .gfp_mask = GFP_KERNEL, > > + .may_unmap = 1, > > + .may_swap = 1, > > + .nr_to_reclaim = ULONG_MAX, > > + .swappiness = vm_swappiness, > > + .order = order, > > + .mem_cgroup = mem_cont, > > + }; > > + > > +loop_again: > > + do_nodes = NODE_MASK_NONE; > > + sc.may_writepage = !laptop_mode; > > + sc.nr_reclaimed = 0; > > + total_scanned = 0; > > + > > + for (priority = DEF_PRIORITY; priority >= 0; priority--) { > > + sc.priority = priority; > > + wmark_ok = false; > > + loop = 0; > > + > > + /* The swap token gets in the way of swapout... */ > > + if (!priority) > > + disable_swap_token(); > > + > > + if (priority == DEF_PRIORITY) > > + do_nodes = node_states[N_ONLINE]; > > + > > + while (1) { > > + nid = mem_cgroup_select_victim_node(mem_cont, > > + &do_nodes); > > + > > + /* Indicate we have cycled the nodelist once > > + * TODO: we might add MAX_RECLAIM_LOOP for > preventing > > + * kswapd burning cpu cycles. > > + */ > > + if (loop == 0) { > > + start_node = nid; > > + loop++; > > + } else if (nid == start_node) > > + break; > > + > > + pgdat = NODE_DATA(nid); > > + balance_pgdat_node(pgdat, order, &sc); > > + total_scanned += sc.nr_scanned; > > + > > + /* Set the node which has at least > > + * one reclaimable zone > > + */ > > + for (i = pgdat->nr_zones - 1; i >= 0; i--) { > > + struct zone *zone = pgdat->node_zones + i; > > + > > + if (!populated_zone(zone)) > > + continue; > > + > > + if (!mem_cgroup_mz_unreclaimable(mem_cont, > > + zone)) > > + break; > > + } > > + if (i < 0) > > + node_clear(nid, do_nodes); > > + > > + if (mem_cgroup_watermark_ok(mem_cont, > > + CHARGE_WMARK_HIGH)) > { > > + wmark_ok = true; > > + goto out; > > + } > > + > > + if (nodes_empty(do_nodes)) { > > + wmark_ok = true; > > + goto out; > > + } > > + } > > + > > + /* All the nodes are unreclaimable, kswapd is done */ > > + if (nodes_empty(do_nodes)) { > > + wmark_ok = true; > > + goto out; > > + } > > + > > + if (total_scanned && priority < DEF_PRIORITY - 2) > > + congestion_wait(WRITE, HZ/10); > > + > > + if (sc.nr_reclaimed >= SWAP_CLUSTER_MAX) > > + break; > > + } > > +out: > > + if (!wmark_ok) { > > + cond_resched(); > > + > > + try_to_freeze(); > > + > > + goto loop_again; > > + } > > + > > + return sc.nr_reclaimed; > > +} > > +#else > > static unsigned long balance_mem_cgroup_pgdat(struct mem_cgroup > *mem_cont, > > int order) > > { > > return 0; > > } > > +#endif > > > > /* > > * The background pageout daemon, started as a kernel thread > > -- > > 1.7.3.1 > > > > -- > > 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 internet charges in Canada: sign > http://stopthemeter.ca/ > > Don't email: email@kvack.org > > > >