On Thu, Apr 21, 2011 at 11:00 PM, KOSAKI Motohiro < kosaki.motohiro@jp.fujitsu.com> 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. After > reclaiming > > each node, it checks mem_cgroup_watermark_ok() and breaks the priority > loop if > > it returns true. > > > > changelog v7..v6: > > 1. change based on KAMAZAWA's patchset. Each memcg reclaims now reclaims > > SWAP_CLUSTER_MAX of pages and putback the memcg to the tail of list. > > memcg-kswapd will visit memcgs in round-robin manner and reduce usages. > > > > changelog v6..v5: > > 1. add mem_cgroup_zone_reclaimable_pages() > > 2. fix some comment style. > > > > changelog v5..v4: > > 1. remove duplicate check on nodes_empty() > > 2. add logic to check if the per-memcg lru is empty on the zone. > > > > changelog v4..v3: > > 1. split the select_victim_node and zone_unreclaimable to a seperate > patches > > 2. remove the logic tries to do zone balancing. > > > > 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 > > Signed-off-by: KAMEZAWA Hiroyuki > > --- > > include/linux/memcontrol.h | 9 +++ > > mm/memcontrol.c | 18 +++++++ > > mm/vmscan.c | 118 > ++++++++++++++++++++++++++++++++++++++++++++ > > 3 files changed, 145 insertions(+), 0 deletions(-) > > > > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h > > index 7444738..39eade6 100644 > > --- a/include/linux/memcontrol.h > > +++ b/include/linux/memcontrol.h > > @@ -115,6 +115,8 @@ extern void mem_cgroup_end_migration(struct > mem_cgroup *mem, > > */ > > int mem_cgroup_inactive_anon_is_low(struct mem_cgroup *memcg); > > int mem_cgroup_inactive_file_is_low(struct mem_cgroup *memcg); > > +unsigned long mem_cgroup_zone_reclaimable_pages(struct mem_cgroup > *memcg, > > + struct zone *zone); > > unsigned long mem_cgroup_zone_nr_pages(struct mem_cgroup *memcg, > > struct zone *zone, > > enum lru_list lru); > > @@ -311,6 +313,13 @@ mem_cgroup_inactive_file_is_low(struct mem_cgroup > *memcg) > > } > > > > static inline unsigned long > > +mem_cgroup_zone_reclaimable_pages(struct mem_cgroup *memcg, > > + struct zone *zone) > > +{ > > + return 0; > > +} > > + > > +static inline unsigned long > > mem_cgroup_zone_nr_pages(struct mem_cgroup *memcg, struct zone *zone, > > enum lru_list lru) > > { > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > > index 4696fd8..41eaa62 100644 > > --- a/mm/memcontrol.c > > +++ b/mm/memcontrol.c > > @@ -1105,6 +1105,24 @@ int mem_cgroup_inactive_file_is_low(struct > mem_cgroup *memcg) > > return (active > inactive); > > } > > > > +unsigned long mem_cgroup_zone_reclaimable_pages(struct mem_cgroup > *memcg, > > + struct zone *zone) > > +{ > > + int nr; > > + int nid = zone_to_nid(zone); > > + int zid = zone_idx(zone); > > + struct mem_cgroup_per_zone *mz = mem_cgroup_zoneinfo(memcg, nid, > zid); > > + > > + nr = MEM_CGROUP_ZSTAT(mz, NR_ACTIVE_FILE) + > > + MEM_CGROUP_ZSTAT(mz, NR_INACTIVE_FILE); > > + > > + if (nr_swap_pages > 0) > > + nr += MEM_CGROUP_ZSTAT(mz, NR_ACTIVE_ANON) + > > + MEM_CGROUP_ZSTAT(mz, NR_INACTIVE_ANON); > > + > > + return nr; > > +} > > + > > unsigned long mem_cgroup_zone_nr_pages(struct mem_cgroup *memcg, > > struct zone *zone, > > enum lru_list lru) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > > index 63c557e..ba03a10 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; > > }; > > Bah! > If you need sc.priority, you have to make cleanup patch at first. and > all current reclaim path have to use sc.priority. Please don't increase > unnecessary mess. > > hmm. so then I would change it by passing the priority > as separate parameter. > > > > > > #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru)) > > @@ -2620,10 +2624,124 @@ 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 shrink_memcg_node(pg_data_t *pgdat, int order, > > + struct scan_control *sc) > > +{ > > + int i; > > + unsigned long total_scanned = 0; > > + struct mem_cgroup *mem_cont = sc->mem_cgroup; > > + int priority = sc->priority; > > unnecessary local variables. we can keep smaller stack. > > ok. > > > + > > + /* > > + * This dma->highmem order is consistant with global reclaim. > > + * We do this because the page allocator works in the opposite > > + * direction although memcg user pages are mostly allocated at > > + * highmem. > > + */ > > + for (i = 0; i < pgdat->nr_zones; i++) { > > + struct zone *zone = pgdat->node_zones + i; > > + unsigned long scan = 0; > > + > > + scan = mem_cgroup_zone_reclaimable_pages(mem_cont, zone); > > + if (!scan) > > + continue; > > + > > + sc->nr_scanned = 0; > > + shrink_zone(priority, zone, sc); > > + total_scanned += sc->nr_scanned; > > + > > + /* > > + * 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; > > please make helper function for may_writepage. iow, don't cut-n-paste. > > hmm, can you help to clarify that? > > > +/* > > + * Per cgroup background reclaim. > > + * TODO: Take off the order since memcg always do order 0 > > + */ > > +static unsigned long shrink_mem_cgroup(struct mem_cgroup *mem_cont, int > order) > > +{ > > + int i, nid, priority, 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 = SWAP_CLUSTER_MAX, > > + .swappiness = vm_swappiness, > > No. memcg has per-memcg swappiness. Please don't use global swappiness > value. > > sounds reasonable, i will take a look at it. > > > + .order = order, > > + .mem_cgroup = mem_cont, > > + }; > > + > > + do_nodes = NODE_MASK_NONE; > > + sc.may_writepage = !laptop_mode; > > + sc.nr_reclaimed = 0; > > this initialization move into sc static initializer. balance pgdat has > loop_again label and this doesn't. > will change. > > > + total_scanned = 0; > > + > > + do_nodes = node_states[N_ONLINE]; > > Why do we need care memoryless node? N_HIGH_MEMORY is wrong? > hmm, let me look into that. > > > + > > + for (priority = DEF_PRIORITY; > > + (priority >= 0) && (sc.nr_to_reclaim > sc.nr_reclaimed); > > + priority--) { > > bah. bad coding style... > ok. will change. > > > + > > + sc.priority = priority; > > + /* The swap token gets in the way of swapout... */ > > + if (!priority) > > + disable_swap_token(); > > Why? > > disable swap token mean "Please devest swap preventation privilege from > owner task. Instead we endure swap storm and performance hit". > However I doublt memcg memory shortage is good situation to make swap > storm. > I am not sure about that either way. we probably can leave as it is and make corresponding change if real problem is observed? > > > > + > > + for (loop = num_online_nodes(); > > + (loop > 0) && !nodes_empty(do_nodes); > > + loop--) { > > Why don't you use for_each_online_node()? > Maybe for_each_node_state(n, N_HIGH_MEMORY) is best option? > > At least, find_next_bit() is efficient than bare loop? > > > + > > + nid = mem_cgroup_select_victim_node(mem_cont, > > + &do_nodes); > > + > > + pgdat = NODE_DATA(nid); > > + shrink_memcg_node(pgdat, order, &sc); > > + total_scanned += sc.nr_scanned; > > + > > + for (i = pgdat->nr_zones - 1; i >= 0; i--) { > > + struct zone *zone = pgdat->node_zones + i; > > + > > + if (populated_zone(zone)) > > + break; > > + } > > memory less node check is here. but we can check it before. > Not sure I understand this, can you help to clarify? thank you for reviewing --Ying > > > + if (i < 0) > > + node_clear(nid, do_nodes); > > + > > + if (mem_cgroup_watermark_ok(mem_cont, > > + CHARGE_WMARK_HIGH)) > > + goto out; > > + } > > + > > + if (total_scanned && priority < DEF_PRIORITY - 2) > > + congestion_wait(WRITE, HZ/10); > > + } > > +out: > > + return sc.nr_reclaimed; > > +} > > +#else > > static unsigned long shrink_mem_cgroup(struct mem_cgroup *mem_cont, int > order) > > { > > return 0; > > } > > +#endif > > > > /* > > * The background pageout daemon, started as a kernel thread > > -- > > 1.7.3.1 > > > > > >