On Thu, 13 Jan 2011 14:00:34 -0800
Ying Han <yinghan@xxxxxxxxxx> wrote:
> The current implementation of memcg only supports direct reclaim and this
> patch adds the support for background reclaim. Per cgroup background reclaim
> is needed which spreads out the memory pressure over longer period of time
> and smoothes out the system performance.
>
> There is a kswapd kernel thread for each memory node. We add a different kswapd
> for each cgroup. The kswapd is sleeping in the wait queue headed at kswapd_wait
> field of a kswapd descriptor.
>
> The kswapd() function now is shared between global and per cgroup kswapd thread.
> It is passed in with the kswapd descriptor which contains the information of
> either node or cgroup. Then the new function balance_mem_cgroup_pgdat is invoked
> if it is per cgroup kswapd thread. The balance_mem_cgroup_pgdat performs a
> priority loop similar to global reclaim. In each iteration it invokes
> balance_pgdat_node for all nodes on the system, which is a 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
> returns true. A per memcg zone will be marked as "unreclaimable" if the scanning
> rate is much greater than the reclaiming rate on the per cgroup LRU. The bit is
> cleared when there is a page charged to the cgroup being freed. Kswapd breaks the
> priority loop if all the zones are marked as "unreclaimable".
>
> Change log v2...v1:
> 1. start/stop the per-cgroup kswapd at create/delete cgroup stage.
> 2. remove checking the wmark from per-page charging. now it checks the wmark
> periodically based on the event counter.
> 3. move the per-cgroup per-zone clear_unreclaimable into uncharge stage.
> 4. shared the kswapd_run/kswapd_stop for per-cgroup and global background
> reclaim.
> 5. name the per-cgroup memcg as "memcg-id" (css->id). And the global kswapd
> keeps the same name.
> 6. fix a race on kswapd_stop while the per-memcg-per-zone info could be accessed
> after freeing.
> 7. add the fairness in zonelist where memcg remember the last zone reclaimed
> from.
>
> Signed-off-by: Ying Han <yinghan@xxxxxxxxxx>
Hmm...at first, I like using workqueue rather than using a thread per memcg.
> ---
> include/linux/memcontrol.h | 37 ++++++
> include/linux/swap.h | 4 +-
> mm/memcontrol.c | 192 ++++++++++++++++++++++++++++-
> mm/vmscan.c | 298 ++++++++++++++++++++++++++++++++++++++++----
> 4 files changed, 504 insertions(+), 27 deletions(-)
>
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index 80a605f..69c6e41 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -25,6 +25,7 @@ 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 {
> @@ -94,6 +95,12 @@ 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 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,
> + nodemask_t *nodes);
>
> static inline
> int mm_match_cgroup(const struct mm_struct *mm, const struct mem_cgroup *cgroup)
> @@ -166,6 +173,12 @@ 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 page_cgroup *pc);
> +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);
> #else /* CONFIG_CGROUP_MEM_RES_CTLR */
> struct mem_cgroup;
>
> @@ -361,6 +374,25 @@ static inline unsigned long mem_cgroup_page_stat(struct mem_cgroup *mem,
> return -ENOSYS;
> }
>
> +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)
> @@ -374,6 +406,11 @@ u64 mem_cgroup_get_limit(struct mem_cgroup *mem)
> return 0;
> }
>
> +static inline bool mem_cgroup_zone_reclaimable(struct mem_cgroup *mem, int nid,
> + int zid)
> +{
> + return false;
> +}
> #endif /* CONFIG_CGROUP_MEM_CONT */
>
> #endif /* _LINUX_MEMCONTROL_H */
> diff --git a/include/linux/swap.h b/include/linux/swap.h
> index 52122fa..b6b5cbb 100644
> --- a/include/linux/swap.h
> +++ b/include/linux/swap.h
> @@ -292,8 +292,8 @@ 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 6ef26a7..e716ece 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -48,6 +48,8 @@
> #include <linux/page_cgroup.h>
> #include <linux/cpu.h>
> #include <linux/oom.h>
> +#include <linux/kthread.h>
> +
> #include "internal.h"
>
> #include <asm/uaccess.h>
> @@ -75,6 +77,7 @@ static int really_do_swap_account __initdata = 1; /* for remember boot option*/
> */
> #define THRESHOLDS_EVENTS_THRESH (7) /* once in 128 */
> #define SOFTLIMIT_EVENTS_THRESH (10) /* once in 1024 */
> +#define WMARK_EVENTS_THRESH (10) /* once in 1024 */
>
> /*
> * Statistics for memory cgroup.
> @@ -131,7 +134,10 @@ 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 */
> + int all_unreclaimable; /* All pages pinned */
> };
> +
> /* Macro for accessing counter */
> #define MEM_CGROUP_ZSTAT(mz, idx) ((mz)->count[(idx)])
>
> @@ -289,8 +295,16 @@ struct mem_cgroup {
> struct mem_cgroup_stat_cpu nocpu_base;
> spinlock_t pcp_counter_lock;
>
> + /*
> + * per cgroup background reclaim.
> + */
> wait_queue_head_t *kswapd_wait;
> unsigned long min_free_kbytes;
> +
> + /* While doing per cgroup background reclaim, we cache the
> + * last node we reclaimed from
> + */
> + int last_scanned_node;
> };
>
> /* Stuffs for move charges at task migration. */
> @@ -380,6 +394,7 @@ static void mem_cgroup_put(struct mem_cgroup *mem);
> static struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *mem);
> static void drain_all_stock_async(void);
> static unsigned long get_min_free_kbytes(struct mem_cgroup *mem);
> +static void wake_memcg_kswapd(struct mem_cgroup *mem);
>
> static struct mem_cgroup_per_zone *
> mem_cgroup_zoneinfo(struct mem_cgroup *mem, int nid, int zid)
> @@ -568,6 +583,12 @@ mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_zone *mctz)
> return mz;
> }
>
> +static void mem_cgroup_check_wmark(struct mem_cgroup *mem)
> +{
> + if (!mem_cgroup_watermark_ok(mem, CHARGE_WMARK_LOW))
> + wake_memcg_kswapd(mem);
> +}
> +
Low for trigger, High for stop ?
> /*
> * Implementation Note: reading percpu statistics for memcg.
> *
> @@ -692,6 +713,8 @@ static void memcg_check_events(struct mem_cgroup *mem, struct page *page)
> mem_cgroup_threshold(mem);
> if (unlikely(__memcg_event_check(mem, SOFTLIMIT_EVENTS_THRESH)))
> mem_cgroup_update_tree(mem, page);
> + if (unlikely(__memcg_event_check(mem, WMARK_EVENTS_THRESH)))
> + mem_cgroup_check_wmark(mem);
> }
This is nice.
> }
>
> @@ -1121,6 +1144,95 @@ 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) * 6;
> + return 0;
> +}
Where does this "*6" come from ? please add comment. Or add macro in header
file and share the value with original.
> +
> +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;
> +}
I think you should check whether this zone has any page.
If no pages in this zone, you can't reclaim any.
> +
> +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 = 1;
> +}
I like boolean for this kind ot true/false value.
> +
> +void mem_cgroup_clear_unreclaimable(struct page_cgroup *pc)
> +{
> + struct mem_cgroup_per_zone *mz = NULL;
> +
> + if (!pc)
> + return;
> +
> + mz = page_cgroup_zoneinfo(pc);
> + if (mz) {
> + mz->pages_scanned = 0;
> + mz->all_unreclaimable = 0;
> + }
> +
> + return;
> +}
> +
> unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
> struct list_head *dst,
> unsigned long *scanned, int order,
> @@ -1773,6 +1885,34 @@ 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, 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);
> +
> + spin_lock(&mem->reclaim_param_lock);
> + mem->last_scanned_node = next_nid;
> + spin_unlock(&mem->reclaim_param_lock);
> +
Is this 'lock' required ?
> + return next_nid;
> +}
> +
> +/*
> * Check OOM-Killer is already running under our hierarchy.
> * If someone is running, return false.
> */
> @@ -2955,6 +3095,7 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype)
> * special functions.
> */
>
> + mem_cgroup_clear_unreclaimable(pc);
> unlock_page_cgroup(pc);
This kind of hook is not good....Can't you do this 'clear' by kswapd in
lazy way ?
> /*
> * even after unlock, we have mem->res.usage here and this memcg
> @@ -3377,7 +3518,7 @@ static int mem_cgroup_resize_limit(struct mem_cgroup *memcg,
> MEM_CGROUP_RECLAIM_SHRINK);
> curusage = res_counter_read_u64(&memcg->res, RES_USAGE);
> /* Usage is reduced ? */
> - if (curusage >= oldusage)
> + if (curusage >= oldusage)
> retry_count--;
> else
> oldusage = curusage;
?
> @@ -3385,6 +3526,9 @@ static int mem_cgroup_resize_limit(struct mem_cgroup *memcg,
> if (!ret && enlarge)
> memcg_oom_recover(memcg);
>
> + if (!mem_cgroup_is_root(memcg) && !memcg->kswapd_wait)
> + kswapd_run(0, memcg);
> +
> return ret;
> }
Hmm, this creates a thread when limit is set....So, tons of threads can be
created. Can't we do this by work_queue ?
Then, the number of threads will be scaled automatically.
>
> @@ -4747,6 +4891,8 @@ 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 = 0;
> }
> return 0;
> }
> @@ -4799,6 +4945,7 @@ static void __mem_cgroup_free(struct mem_cgroup *mem)
> {
> int node;
>
> + kswapd_stop(0, mem);
> mem_cgroup_remove_from_trees(mem);
> free_css_id(&mem_cgroup_subsys, &mem->css);
>
> @@ -4867,6 +5014,48 @@ 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);
> +}
> +
> +wait_queue_head_t *mem_cgroup_kswapd_wait(struct mem_cgroup *mem)
> +{
> + if (!mem)
> + return NULL;
> +
> + return mem->kswapd_wait;
> +}
> +
> +int mem_cgroup_last_scanned_node(struct mem_cgroup *mem)
> +{
> + if (!mem)
> + return -1;
> +
> + return mem->last_scanned_node;
> +}
> +
> +static void wake_memcg_kswapd(struct mem_cgroup *mem)
> +{
> + wait_queue_head_t *wait;
> +
> + if (!mem)
> + return;
> +
> + wait = mem->kswapd_wait;
> +
> + if (!waitqueue_active(wait))
> + return;
> +
> + wake_up_interruptible(wait);
> +}
> +
> static int mem_cgroup_soft_limit_tree_init(void)
> {
> struct mem_cgroup_tree_per_node *rtpn;
> @@ -4942,6 +5131,7 @@ 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;
If we always start from 0 at the first run, I think this can be 0 at default.
> spin_lock_init(&mem->reclaim_param_lock);
> INIT_LIST_HEAD(&mem->oom_notify);
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index a53d91d..34f6165 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -46,6 +46,8 @@
>
> #include <linux/swapops.h>
>
> +#include <linux/res_counter.h>
> +
> #include "internal.h"
>
> #define CREATE_TRACE_POINTS
> @@ -98,6 +100,8 @@ struct scan_control {
> * are scanned.
> */
> nodemask_t *nodemask;
> +
> + int priority;
> };
>
> #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
> @@ -1385,6 +1389,9 @@ shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone,
> ISOLATE_INACTIVE : ISOLATE_BOTH,
> 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.
> @@ -1504,6 +1511,7 @@ 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;
> @@ -2127,11 +2135,19 @@ static int sleeping_prematurely(struct kswapd *kswapd, int order,
> {
> int i;
> 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 1;
>
> + /* If after HZ/10, the cgroup is below the high wmark, it's premature */
> + if (mem) {
> + if (!mem_cgroup_watermark_ok(mem, CHARGE_WMARK_HIGH))
> + return 1;
> + return 0;
> + }
> +
> /* If after HZ/10, a zone is below the high mark, it's premature */
> for (i = 0; i < pgdat->nr_zones; i++) {
> struct zone *zone = pgdat->node_zones + i;
> @@ -2370,6 +2386,212 @@ out:
> return sc.nr_reclaimed;
> }
>
> +#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);
I think you can check per-zone memory usage here and compare it with
the value in previous run which set mz->all_unreclaimable.
If current_zone_usage < mz->usage_in_previous_run, you can clear
all_unreclaimable without hooks.
But please note that 'uncharge' doesn't mean pages turned to be reclaimable.
I'm not sure there are better hint or not.
> +
> + end_zone = i;
> + goto scan;
> + }
> + 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;
> + int wmark_ok;
> + int loop = 0;
> + pg_data_t *pgdat;
> + nodemask_t do_nodes;
> + unsigned long total_scanned = 0;
> + 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 = 0;
> + 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 = 1;
> + goto out;
> + }
> +
> + if (nodes_empty(do_nodes)) {
> + wmark_ok = 1;
> + goto out;
> + }
> + }
> +
> + /* All the nodes are unreclaimable, kswapd is done */
> + if (nodes_empty(do_nodes)) {
> + wmark_ok = 1;
> + 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
> * from the init process.
> @@ -2388,6 +2610,7 @@ int kswapd(void *p)
> unsigned long order;
> 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;
> DEFINE_WAIT(wait);
> @@ -2430,8 +2653,10 @@ int kswapd(void *p)
> if (is_node_kswapd(kswapd_p)) {
> new_order = pgdat->kswapd_max_order;
> pgdat->kswapd_max_order = 0;
> - } else
> + } else {
> + /* mem cgroup does order 0 charging always */
> new_order = 0;
> + }
>
> if (order < new_order) {
> /*
> @@ -2492,8 +2717,12 @@ int kswapd(void *p)
> * after returning from the refrigerator
> */
> if (!ret) {
> - trace_mm_vmscan_kswapd_wake(pgdat->node_id, order);
> - balance_pgdat(pgdat, order);
> + if (is_node_kswapd(kswapd_p)) {
> + trace_mm_vmscan_kswapd_wake(pgdat->node_id,
> + order);
> + balance_pgdat(pgdat, order);
> + } else
> + balance_mem_cgroup_pgdat(mem, order);
> }
> }
> return 0;
> @@ -2635,60 +2864,81 @@ 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.
> + * This kswapd start function will be called by init, node-hot-add and memcg
> + * limiting. 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 *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;
> - 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);
> + }
This naming is good and fits TASK_COMM_LEN.
Thank you for your effort.
-Kame
> +
> + thr = kthread_run(kswapd, kswapd_p, name);
> if (IS_ERR(thr)) {
> /* failure at boot is fatal */
> BUG_ON(system_state == SYSTEM_BOOTING);
> - printk("Failed to start kswapd on node %d\n",nid);
> ret = -1;
> - }
> - kswapd_p->kswapd_task = thr;
> + } else
> + kswapd_p->kswapd_task = thr;
> return ret;
> }
>
> /*
> * Called by memory hotplug when all memory in a node is offlined.
> + * Also called by memcg when the cgroup is deleted.
> */
> -void kswapd_stop(int nid)
> +void kswapd_stop(int nid, struct mem_cgroup *mem)
> {
> struct task_struct *thr = NULL;
> struct kswapd *kswapd_p = NULL;
> wait_queue_head_t *wait;
>
> - pg_data_t *pgdat = NODE_DATA(nid);
> -
> spin_lock(&kswapds_spinlock);
> - wait = pgdat->kswapd_wait;
> + if (!mem) {
> + pg_data_t *pgdat = NODE_DATA(nid);
> + wait = pgdat->kswapd_wait;
> + } else
> + wait = mem_cgroup_kswapd_wait(mem);
> +
> if (wait) {
> kswapd_p = container_of(wait, struct kswapd, kswapd_wait);
> thr = kswapd_p->kswapd_task;
> }
> spin_unlock(&kswapds_spinlock);
>
> - if (thr)
> - kthread_stop(thr);
> -
> - kfree(kswapd_p);
> + if (kswapd_p) {
> + if (thr)
> + kthread_stop(thr);
> + kfree(kswapd_p);
> + }
> }
>
> static int __init kswapd_init(void)
> @@ -2697,7 +2947,7 @@ 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
>
>
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