On Sun, Apr 17, 2011 at 7:11 PM, Minchan Kim wrote: > On Sat, Apr 16, 2011 at 8:23 AM, Ying Han wrote: > > Add the kswapd_mem field in kswapd descriptor which links the kswapd > > kernel thread to a memcg. The per-memcg kswapd is sleeping in the wait > > queue headed at kswapd_wait field of the kswapd descriptor. > > > > The kswapd() function is now shared between global and per-memcg kswapd. > It > > is passed in with the kswapd descriptor which contains the information of > > either node or memcg. Then the new function balance_mem_cgroup_pgdat is > > invoked if it is per-mem kswapd thread, and the implementation of the > function > > is on the following patch. > > > > changelog v4..v3: > > 1. fix up the kswapd_run and kswapd_stop for online_pages() and > offline_pages. > > 2. drop the PF_MEMALLOC flag for memcg kswapd for now per KAMAZAWA's > request. > > > > changelog v3..v2: > > 1. split off from the initial patch which includes all changes of the > following > > three patches. > > > > Signed-off-by: Ying Han > > --- > > include/linux/memcontrol.h | 5 ++ > > include/linux/swap.h | 5 +- > > mm/memcontrol.c | 29 ++++++++ > > mm/memory_hotplug.c | 4 +- > > mm/vmscan.c | 156 > ++++++++++++++++++++++++++++++-------------- > > 5 files changed, 147 insertions(+), 52 deletions(-) > > > > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h > > index 3ece36d..f7ffd1f 100644 > > --- a/include/linux/memcontrol.h > > +++ b/include/linux/memcontrol.h > > @@ -24,6 +24,7 @@ struct mem_cgroup; > > struct page_cgroup; > > struct page; > > struct mm_struct; > > +struct kswapd; > > > > /* Stats that can be updated by kernel. */ > > enum mem_cgroup_page_stat_item { > > @@ -83,6 +84,10 @@ int task_in_mem_cgroup(struct task_struct *task, const > struct mem_cgroup *mem); > > extern struct mem_cgroup *try_get_mem_cgroup_from_page(struct page > *page); > > extern struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p); > > extern int mem_cgroup_watermark_ok(struct mem_cgroup *mem, int > charge_flags); > > +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); > > > > static inline > > int mm_match_cgroup(const struct mm_struct *mm, const struct mem_cgroup > *cgroup) > > diff --git a/include/linux/swap.h b/include/linux/swap.h > > index f43d406..17e0511 100644 > > --- a/include/linux/swap.h > > +++ b/include/linux/swap.h > > @@ -30,6 +30,7 @@ struct kswapd { > > struct task_struct *kswapd_task; > > wait_queue_head_t kswapd_wait; > > pg_data_t *kswapd_pgdat; > > + struct mem_cgroup *kswapd_mem; > > }; > > > > int kswapd(void *p); > > @@ -303,8 +304,8 @@ static inline void > scan_unevictable_unregister_node(struct node *node) > > } > > #endif > > > > -extern int kswapd_run(int nid); > > -extern void kswapd_stop(int nid); > > +extern int kswapd_run(int nid, struct mem_cgroup *mem); > > +extern void kswapd_stop(int nid, struct mem_cgroup *mem); > > > > #ifdef CONFIG_MMU > > /* linux/mm/shmem.c */ > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > > index 76ad009..8761a6f 100644 > > --- a/mm/memcontrol.c > > +++ b/mm/memcontrol.c > > @@ -278,6 +278,8 @@ struct mem_cgroup { > > */ > > u64 high_wmark_distance; > > u64 low_wmark_distance; > > + > > + wait_queue_head_t *kswapd_wait; > > > Like I mentioned in [1/10], personally, I like including kswapd > instead of kswapd_wait. Just personal opinion. Feel free to ignore. > thank you for your comments. If that makes more sense, I am ok to make the change. But I would like to keep this as the current version and do a separate change after the basic stuff in. Hope that works. > > > }; > > > > /* Stuffs for move charges at task migration. */ > > @@ -4670,6 +4672,33 @@ int mem_cgroup_watermark_ok(struct mem_cgroup > *mem, > > return ret; > > } > > > > +int mem_cgroup_init_kswapd(struct mem_cgroup *mem, struct kswapd > *kswapd_p) > > +{ > > + if (!mem || !kswapd_p) > > + return 0; > > + > > + mem->kswapd_wait = &kswapd_p->kswapd_wait; > > + kswapd_p->kswapd_mem = mem; > > + > > + return css_id(&mem->css); > > +} > > + > > +void mem_cgroup_clear_kswapd(struct mem_cgroup *mem) > > +{ > > + if (mem) > > + mem->kswapd_wait = NULL; > > + > > + return; > > +} > > + > > +wait_queue_head_t *mem_cgroup_kswapd_wait(struct mem_cgroup *mem) > > +{ > > + if (!mem) > > + return NULL; > > + > > + return mem->kswapd_wait; > > +} > > + > > static int mem_cgroup_soft_limit_tree_init(void) > > { > > struct mem_cgroup_tree_per_node *rtpn; > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > > index 321fc74..2f78ff6 100644 > > --- a/mm/memory_hotplug.c > > +++ b/mm/memory_hotplug.c > > @@ -462,7 +462,7 @@ int online_pages(unsigned long pfn, unsigned long > nr_pages) > > setup_per_zone_wmarks(); > > calculate_zone_inactive_ratio(zone); > > if (onlined_pages) { > > - kswapd_run(zone_to_nid(zone)); > > + kswapd_run(zone_to_nid(zone), NULL); > > node_set_state(zone_to_nid(zone), N_HIGH_MEMORY); > > } > > > > @@ -897,7 +897,7 @@ repeat: > > calculate_zone_inactive_ratio(zone); > > if (!node_present_pages(node)) { > > node_clear_state(node, N_HIGH_MEMORY); > > - kswapd_stop(node); > > + kswapd_stop(node, NULL); > > } > > > > vm_total_pages = nr_free_pagecache_pages(); > > diff --git a/mm/vmscan.c b/mm/vmscan.c > > index 61fb96e..06036d2 100644 > > --- a/mm/vmscan.c > > +++ b/mm/vmscan.c > > @@ -2241,6 +2241,8 @@ static bool pgdat_balanced(pg_data_t *pgdat, > unsigned long balanced_pages, > > return balanced_pages > (present_pages >> 2); > > } > > > > +#define is_node_kswapd(kswapd_p) (!(kswapd_p)->kswapd_mem) > > In memcg, we already have a similar thing "scanning_global_lru". > How about using "global" term? > hmm. ok. > > > + > > /* is kswapd sleeping prematurely? */ > > static int sleeping_prematurely(struct kswapd *kswapd, int order, > > long remaining, int classzone_idx) > > @@ -2249,11 +2251,16 @@ static int sleeping_prematurely(struct kswapd > *kswapd, int order, > > unsigned long balanced = 0; > > bool all_zones_ok = true; > > pg_data_t *pgdat = kswapd->kswapd_pgdat; > > + struct mem_cgroup *mem = kswapd->kswapd_mem; > > > > /* If a direct reclaimer woke kswapd within HZ/10, it's premature > */ > > if (remaining) > > return true; > > > > + /* Doesn't support for per-memcg reclaim */ > > + if (mem) > > + return false; > > + > > How about is_global_kswapd instead of checking wheterh mem field is NULL or > not? > make sense. will change. > > > /* Check the watermark levels */ > > for (i = 0; i < pgdat->nr_zones; i++) { > > struct zone *zone = pgdat->node_zones + i; > > @@ -2596,19 +2603,25 @@ static void kswapd_try_to_sleep(struct kswapd > *kswapd_p, int order, > > * go fully to sleep until explicitly woken up. > > */ > > if (!sleeping_prematurely(kswapd_p, order, remaining, > classzone_idx)) { > > - trace_mm_vmscan_kswapd_sleep(pgdat->node_id); > > + if (is_node_kswapd(kswapd_p)) { > > + trace_mm_vmscan_kswapd_sleep(pgdat->node_id); > > > > - /* > > - * vmstat counters are not perfectly accurate and the > estimated > > - * value for counters such as NR_FREE_PAGES can deviate > from the > > - * true value by nr_online_cpus * threshold. To avoid the > zone > > - * watermarks being breached while under pressure, we > reduce the > > - * per-cpu vmstat threshold while kswapd is awake and > restore > > - * them before going back to sleep. > > - */ > > - set_pgdat_percpu_threshold(pgdat, > calculate_normal_threshold); > > - schedule(); > > - set_pgdat_percpu_threshold(pgdat, > calculate_pressure_threshold); > > + /* > > + * vmstat counters are not perfectly accurate and > the > > + * estimated value for counters such as > NR_FREE_PAGES > > + * can deviate from the true value by > nr_online_cpus * > > + * threshold. To avoid the zone watermarks being > > + * breached while under pressure, we reduce the > per-cpu > > + * vmstat threshold while kswapd is awake and > restore > > + * them before going back to sleep. > > + */ > > + set_pgdat_percpu_threshold(pgdat, > > + > calculate_normal_threshold); > > + schedule(); > > + set_pgdat_percpu_threshold(pgdat, > > + > calculate_pressure_threshold); > > + } else > > + schedule(); > > } else { > > if (remaining) > > count_vm_event(KSWAPD_LOW_WMARK_HIT_QUICKLY); > > @@ -2618,6 +2631,12 @@ static void kswapd_try_to_sleep(struct kswapd > *kswapd_p, int order, > > finish_wait(wait_h, &wait); > > } > > > > +static unsigned long balance_mem_cgroup_pgdat(struct mem_cgroup > *mem_cont, > > + int order) > > +{ > > + return 0; > > +} > > + > > /* > > * The background pageout daemon, started as a kernel thread > > * from the init process. > > @@ -2637,6 +2656,7 @@ int kswapd(void *p) > > int classzone_idx; > > struct kswapd *kswapd_p = (struct kswapd *)p; > > pg_data_t *pgdat = kswapd_p->kswapd_pgdat; > > + struct mem_cgroup *mem = kswapd_p->kswapd_mem; > > wait_queue_head_t *wait_h = &kswapd_p->kswapd_wait; > > struct task_struct *tsk = current; > > > > @@ -2647,10 +2667,12 @@ int kswapd(void *p) > > > > lockdep_set_current_reclaim_state(GFP_KERNEL); > > > > - BUG_ON(pgdat->kswapd_wait != wait_h); > > - cpumask = cpumask_of_node(pgdat->node_id); > > - if (!cpumask_empty(cpumask)) > > - set_cpus_allowed_ptr(tsk, cpumask); > > + if (is_node_kswapd(kswapd_p)) { > > + BUG_ON(pgdat->kswapd_wait != wait_h); > > + cpumask = cpumask_of_node(pgdat->node_id); > > + if (!cpumask_empty(cpumask)) > > + set_cpus_allowed_ptr(tsk, cpumask); > > + } > > current->reclaim_state = &reclaim_state; > > > > /* > > @@ -2665,7 +2687,10 @@ int kswapd(void *p) > > * us from recursively trying to free more memory as we're > > * trying to free the first piece of memory in the first place). > > */ > > - tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD; > > + if (is_node_kswapd(kswapd_p)) > > + tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD; > > + else > > + tsk->flags |= PF_SWAPWRITE | PF_KSWAPD; > > set_freezable(); > > > > order = 0; > > @@ -2675,24 +2700,29 @@ int kswapd(void *p) > > int new_classzone_idx; > > int ret; > > > > - new_order = pgdat->kswapd_max_order; > > - new_classzone_idx = pgdat->classzone_idx; > > - pgdat->kswapd_max_order = 0; > > - pgdat->classzone_idx = MAX_NR_ZONES - 1; > > - if (order < new_order || classzone_idx > > new_classzone_idx) { > > - /* > > - * Don't sleep if someone wants a larger 'order' > > - * allocation or has tigher zone constraints > > - */ > > - order = new_order; > > - classzone_idx = new_classzone_idx; > > - } else { > > - kswapd_try_to_sleep(kswapd_p, order, > classzone_idx); > > - order = pgdat->kswapd_max_order; > > - classzone_idx = pgdat->classzone_idx; > > + if (is_node_kswapd(kswapd_p)) { > > + new_order = pgdat->kswapd_max_order; > > + new_classzone_idx = pgdat->classzone_idx; > > pgdat->kswapd_max_order = 0; > > pgdat->classzone_idx = MAX_NR_ZONES - 1; > > - } > > + if (order < new_order || > > + classzone_idx > > new_classzone_idx) { > > + /* > > + * Don't sleep if someone wants a larger > 'order' > > + * allocation or has tigher zone > constraints > > + */ > > + order = new_order; > > + classzone_idx = new_classzone_idx; > > + } else { > > + kswapd_try_to_sleep(kswapd_p, order, > > + classzone_idx); > > + order = pgdat->kswapd_max_order; > > + classzone_idx = pgdat->classzone_idx; > > + pgdat->kswapd_max_order = 0; > > + pgdat->classzone_idx = MAX_NR_ZONES - 1; > > + } > > + } else > > + kswapd_try_to_sleep(kswapd_p, order, > classzone_idx); > > > > ret = try_to_freeze(); > > if (kthread_should_stop()) > > @@ -2703,8 +2733,13 @@ int kswapd(void *p) > > * after returning from the refrigerator > > */ > > if (!ret) { > > - trace_mm_vmscan_kswapd_wake(pgdat->node_id, > order); > > - order = balance_pgdat(pgdat, order, > &classzone_idx); > > + if (is_node_kswapd(kswapd_p)) { > > + > trace_mm_vmscan_kswapd_wake(pgdat->node_id, > > + order); > > + order = balance_pgdat(pgdat, order, > > + &classzone_idx); > > + } else > > + balance_mem_cgroup_pgdat(mem, order); > > } > > } > > return 0; > > @@ -2849,30 +2884,53 @@ static int __devinit cpu_callback(struct > notifier_block *nfb, > > * This kswapd start function will be called by init and node-hot-add. > > * On node-hot-add, kswapd will moved to proper cpus if cpus are > hot-added. > > */ > > -int kswapd_run(int nid) > > +int kswapd_run(int nid, struct mem_cgroup *mem) > > { > > - pg_data_t *pgdat = NODE_DATA(nid); > > struct task_struct *kswapd_thr; > > + pg_data_t *pgdat = NULL; > > struct kswapd *kswapd_p; > > + static char name[TASK_COMM_LEN]; > > + int memcg_id; > > int ret = 0; > > > > - if (pgdat->kswapd_wait) > > - return 0; > > + if (!mem) { > > + pgdat = NODE_DATA(nid); > > + if (pgdat->kswapd_wait) > > + return ret; > > + } > > > > kswapd_p = kzalloc(sizeof(struct kswapd), GFP_KERNEL); > > if (!kswapd_p) > > return -ENOMEM; > > > > init_waitqueue_head(&kswapd_p->kswapd_wait); > > - pgdat->kswapd_wait = &kswapd_p->kswapd_wait; > > - kswapd_p->kswapd_pgdat = pgdat; > > > > - kswapd_thr = kthread_run(kswapd, kswapd_p, "kswapd%d", nid); > > + if (!mem) { > > + pgdat->kswapd_wait = &kswapd_p->kswapd_wait; > > + kswapd_p->kswapd_pgdat = pgdat; > > + snprintf(name, TASK_COMM_LEN, "kswapd_%d", nid); > > + } else { > > + memcg_id = mem_cgroup_init_kswapd(mem, kswapd_p); > > + if (!memcg_id) { > > + kfree(kswapd_p); > > + return ret; > > + } > > + snprintf(name, TASK_COMM_LEN, "memcg_%d", memcg_id); > > + } > > + > > + kswapd_thr = kthread_run(kswapd, kswapd_p, name); > > if (IS_ERR(kswapd_thr)) { > > /* failure at boot is fatal */ > > BUG_ON(system_state == SYSTEM_BOOTING); > > - printk("Failed to start kswapd on node %d\n",nid); > > - pgdat->kswapd_wait = NULL; > > + if (!mem) { > > + printk(KERN_ERR "Failed to start kswapd on node > %d\n", > > + nid); > > + pgdat->kswapd_wait = NULL; > > + } else { > > + printk(KERN_ERR "Failed to start kswapd on memcg > %d\n", > > + > memcg_id); > > + mem_cgroup_clear_kswapd(mem); > > + } > > kfree(kswapd_p); > > ret = -1; > > } else > > @@ -2883,15 +2941,17 @@ int kswapd_run(int nid) > > /* > > * Called by memory hotplug when all memory in a node is offlined. > > */ > > -void kswapd_stop(int nid) > > +void kswapd_stop(int nid, struct mem_cgroup *mem) > > { > > struct task_struct *kswapd_thr = NULL; > > struct kswapd *kswapd_p = NULL; > > wait_queue_head_t *wait; > > > > - pg_data_t *pgdat = NODE_DATA(nid); > > + if (!mem) > > + wait = NODE_DATA(nid)->kswapd_wait; > > + else > > + wait = mem_cgroup_kswapd_wait(mem); > > > > - wait = pgdat->kswapd_wait; > > if (wait) { > > kswapd_p = container_of(wait, struct kswapd, kswapd_wait); > > kswapd_thr = kswapd_p->kswapd_task; > > @@ -2910,7 +2970,7 @@ static int __init kswapd_init(void) > > > > swap_setup(); > > for_each_node_state(nid, N_HIGH_MEMORY) > > - kswapd_run(nid); > > + kswapd_run(nid, NULL); > > hotcpu_notifier(cpu_callback, 0); > > return 0; > > } > > -- > > 1.7.3.1 > > > > > > Let me ask a question. > > What's the effect of kswapd_try_to_sleep in memcg? > > As I look code, sleeping_prematurely always return false in case of > memcg. that is right. > So kswapd_try_to_sleep can sleep short time and then sleep > until next wakeup. It means it doesn't have any related to > kswapd_try_to_sleep's goal. So I hope you remove hack of memcg in > kswapd_try_to_sleep and just calling schedule in kswapd function for > sleeping memcg_kswapd. > But I don't look at further patches in series so I may miss something. No, you are not missing something. The memcg kswapd doesn't have the sleeping_prematurely logic in this patch. I was thinking to add similar check on zone->all_unreclaimable but instead check all the zones per-memcg. That sounds like much overhead to me, so I simply put the schedule() for memcg in this patch but changed the APIs kswapd_try_to_sleep, and sleeping_prematurely only. I might be able to revert those two API changes from this patch, and add them later as part of the real memcg sleeping_prematurely patch. --Ying > -- > Kind regards, > Minchan Kim >