On Tue, 21 Feb 2012 15:34:37 +0400
Glauber Costa <glommer@xxxxxxxxxxxxx> wrote:
> This patch adds the shrinker interface to memcg proposed kmem
> controller. With this, softlimits starts being meaningful. I didn't
> played to much with softlimits itself, since it is a bit in progress
> for the general case as well. But this patch at least makes vmscan.c
> no longer skip shrink_slab for the memcg case.
>
> It also allows us to set the hard limit to a lower value than
> current usage, as it is possible for the current memcg: a reclaim
> is carried on, and if we succeed in freeing enough of kernel memory,
> we can lower the limit.
>
> Signed-off-by: Glauber Costa <glommer@xxxxxxxxxxxxx>
> CC: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx>
> CC: Greg Thelen <gthelen@xxxxxxxxxx>
> CC: Johannes Weiner <jweiner@xxxxxxxxxx>
> CC: Michal Hocko <mhocko@xxxxxxx>
> CC: Hiroyouki Kamezawa <kamezawa.hiroyu@xxxxxxxxxxxxxx>
> CC: Paul Turner <pjt@xxxxxxxxxx>
> CC: Frederic Weisbecker <fweisbec@xxxxxxxxx>
> CC: Pekka Enberg <penberg@xxxxxxxxxx>
> CC: Christoph Lameter <cl@xxxxxxxxx>
> ---
> include/linux/memcontrol.h | 5 +++
> include/linux/shrinker.h | 4 ++
> mm/memcontrol.c | 87 ++++++++++++++++++++++++++++++++++++++++++--
> mm/vmscan.c | 60 +++++++++++++++++++++++++++++--
> 4 files changed, 150 insertions(+), 6 deletions(-)
>
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index 6138d10..246b2d4 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -33,12 +33,16 @@ struct mm_struct;
> struct memcg_kmem_cache {
> struct kmem_cache *cache;
> struct work_struct destroy;
> + struct list_head lru;
> + u32 nr_objects;
> struct mem_cgroup *memcg; /* Should be able to do without this */
> };
>
> struct memcg_cache_struct {
> int index;
> struct kmem_cache *cache;
> + int (*shrink_fn)(struct shrinker *shrink, struct shrink_control *sc);
> + struct shrinker shrink;
> };
>
> enum memcg_cache_indexes {
> @@ -53,6 +57,7 @@ struct mem_cgroup *memcg_from_shrinker(struct shrinker *s);
> struct memcg_kmem_cache *memcg_cache_get(struct mem_cgroup *memcg, int index);
> void register_memcg_cache(struct memcg_cache_struct *cache);
> void memcg_slab_destroy(struct kmem_cache *cache, struct mem_cgroup *memcg);
> +bool memcg_slab_reclaim(struct mem_cgroup *memcg);
>
> struct kmem_cache *
> kmem_cache_dup(struct mem_cgroup *memcg, struct kmem_cache *base);
> diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h
> index 07ceb97..11efdba 100644
> --- a/include/linux/shrinker.h
> +++ b/include/linux/shrinker.h
> @@ -1,6 +1,7 @@
> #ifndef _LINUX_SHRINKER_H
> #define _LINUX_SHRINKER_H
>
> +struct mem_cgroup;
> /*
> * This struct is used to pass information from page reclaim to the shrinkers.
> * We consolidate the values for easier extention later.
> @@ -10,6 +11,7 @@ struct shrink_control {
>
> /* How many slab objects shrinker() should scan and try to reclaim */
> unsigned long nr_to_scan;
> + struct mem_cgroup *memcg;
> };
>
> /*
> @@ -40,4 +42,6 @@ struct shrinker {
> #define DEFAULT_SEEKS 2 /* A good number if you don't know better. */
> extern void register_shrinker(struct shrinker *);
> extern void unregister_shrinker(struct shrinker *);
> +
> +extern void register_shrinker_memcg(struct shrinker *);
> #endif
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 1b1db88..9c89a3c 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -3460,6 +3460,54 @@ static int mem_cgroup_resize_limit(struct mem_cgroup *memcg,
> return ret;
> }
>
> +static int mem_cgroup_resize_kmem_limit(struct mem_cgroup *memcg,
> + unsigned long long val)
> +{
> +
> + int retry_count;
> + int ret = 0;
> + int children = mem_cgroup_count_children(memcg);
> + u64 curusage, oldusage;
> +
> + struct shrink_control shrink = {
> + .gfp_mask = GFP_KERNEL,
> + .memcg = memcg,
> + };
> +
> + /*
> + * For keeping hierarchical_reclaim simple, how long we should retry
> + * is depends on callers. We set our retry-count to be function
> + * of # of children which we should visit in this loop.
> + */
> + retry_count = MEM_CGROUP_RECLAIM_RETRIES * children;
> +
> + oldusage = res_counter_read_u64(&memcg->kmem, RES_USAGE);
> +
> + while (retry_count) {
> + if (signal_pending(current)) {
> + ret = -EINTR;
> + break;
> + }
> + mutex_lock(&set_limit_mutex);
> + ret = res_counter_set_limit(&memcg->kmem, val);
> + mutex_unlock(&set_limit_mutex);
> + if (!ret)
> + break;
> +
> + shrink_slab(&shrink, 0, 0);
> +
> + curusage = res_counter_read_u64(&memcg->kmem, RES_USAGE);
> +
> + /* Usage is reduced ? */
> + if (curusage >= oldusage)
> + retry_count--;
> + else
> + oldusage = curusage;
> + }
> + return ret;
> +
> +}
> +
> static int mem_cgroup_resize_memsw_limit(struct mem_cgroup *memcg,
> unsigned long long val)
> {
> @@ -3895,13 +3943,17 @@ static int mem_cgroup_write(struct cgroup *cont, struct cftype *cft,
> break;
> if (type == _MEM)
> ret = mem_cgroup_resize_limit(memcg, val);
> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
> else if (type == _KMEM) {
> if (!memcg->kmem_independent_accounting) {
> ret = -EINVAL;
> break;
> }
> - ret = res_counter_set_limit(&memcg->kmem, val);
> - } else
> +
> + ret = mem_cgroup_resize_kmem_limit(memcg, val);
> + }
> +#endif
> + else
> ret = mem_cgroup_resize_memsw_limit(memcg, val);
> break;
> case RES_SOFT_LIMIT:
> @@ -5007,9 +5059,19 @@ struct memcg_kmem_cache *memcg_cache_get(struct mem_cgroup *memcg, int index)
>
> void register_memcg_cache(struct memcg_cache_struct *cache)
> {
> + struct shrinker *shrink;
> +
> BUG_ON(kmem_avail_caches[cache->index]);
>
> kmem_avail_caches[cache->index] = cache;
> + if (!kmem_avail_caches[cache->index]->shrink_fn)
> + return;
> +
> + shrink = &kmem_avail_caches[cache->index]->shrink;
> + shrink->seeks = DEFAULT_SEEKS;
> + shrink->shrink = kmem_avail_caches[cache->index]->shrink_fn;
> + shrink->batch = 1024;
> + register_shrinker_memcg(shrink);
> }
>
> #define memcg_kmem(memcg) \
> @@ -5055,8 +5117,21 @@ int memcg_kmem_newpage(struct mem_cgroup *memcg, struct page *page, unsigned lon
> {
> unsigned long size = pages << PAGE_SHIFT;
> struct res_counter *fail;
> + int ret;
> + bool do_softlimit;
> +
> + ret = res_counter_charge(memcg_kmem(memcg), size, &fail);
> + if (unlikely(mem_cgroup_event_ratelimit(memcg,
> + MEM_CGROUP_TARGET_THRESH))) {
> +
> + do_softlimit = mem_cgroup_event_ratelimit(memcg,
> + MEM_CGROUP_TARGET_SOFTLIMIT);
> + mem_cgroup_threshold(memcg);
> + if (unlikely(do_softlimit))
> + mem_cgroup_update_tree(memcg, page);
> + }
Do we need to have this hook here ?
(BTW, please don't duplicate...)
>
> - return res_counter_charge(memcg_kmem(memcg), size, &fail);
> + return ret;
> }
>
> void memcg_kmem_freepage(struct mem_cgroup *memcg, struct page *page, unsigned long pages)
> @@ -5083,6 +5158,7 @@ void memcg_create_kmem_caches(struct mem_cgroup *memcg)
> else
> memcg->kmem_cache[i].cache = kmem_cache_dup(memcg, cache);
> INIT_WORK(&memcg->kmem_cache[i].destroy, memcg_cache_destroy);
> + INIT_LIST_HEAD(&memcg->kmem_cache[i].lru);
> memcg->kmem_cache[i].memcg = memcg;
> }
> }
> @@ -5157,6 +5233,11 @@ free_out:
> return ERR_PTR(error);
> }
>
> +bool memcg_slab_reclaim(struct mem_cgroup *memcg)
> +{
> + return !memcg->kmem_independent_accounting;
> +}
> +
> void memcg_slab_destroy(struct kmem_cache *cache, struct mem_cgroup *memcg)
> {
> int i;
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index c52b235..b9bceb6 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -159,6 +159,23 @@ long vm_total_pages; /* The total number of pages which the VM controls */
> static LIST_HEAD(shrinker_list);
> static DECLARE_RWSEM(shrinker_rwsem);
>
> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
> +/*
> + * If we could guarantee the root mem cgroup will always exist, we could just
> + * use the normal shrinker_list, and assume that the root memcg is passed
> + * as a parameter. But we're not quite there yet. Because of that, the shinkers
> + * from the memcg case can be different from the normal shrinker for the same
> + * object. This is not the ideal situation but is a step towards that.
> + *
> + * Also, not all caches will have their memcg version (also likely to change),
> + * so scanning the whole list is a waste.
> + *
> + * I am using, however, the same lock for both lists. Updates to it should
> + * be unfrequent, so I don't expect that to generate contention
> + */
> +static LIST_HEAD(shrinker_memcg_list);
> +#endif
> +
> #ifdef CONFIG_CGROUP_MEM_RES_CTLR
> static bool global_reclaim(struct scan_control *sc)
> {
> @@ -169,6 +186,11 @@ static bool scanning_global_lru(struct mem_cgroup_zone *mz)
> {
> return !mz->mem_cgroup;
> }
> +
> +static bool global_slab_reclaim(struct scan_control *sc)
> +{
> + return !memcg_slab_reclaim(sc->target_mem_cgroup);
> +}
Do we need this new function ? global_reclaim() isn't enough ?
Thanks,
-Kame
> #else
> static bool global_reclaim(struct scan_control *sc)
> {
> @@ -179,6 +201,11 @@ static bool scanning_global_lru(struct mem_cgroup_zone *mz)
> {
> return true;
> }
> +
> +static bool global_slab_reclaim(struct scan_control *sc)
> +{
> + return true;
> +}
> #endif
>
> static struct zone_reclaim_stat *get_reclaim_stat(struct mem_cgroup_zone *mz)
> @@ -225,6 +252,16 @@ void unregister_shrinker(struct shrinker *shrinker)
> }
> EXPORT_SYMBOL(unregister_shrinker);
>
> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
> +void register_shrinker_memcg(struct shrinker *shrinker)
> +{
> + atomic_long_set(&shrinker->nr_in_batch, 0);
> + down_write(&shrinker_rwsem);
> + list_add_tail(&shrinker->list, &shrinker_memcg_list);
> + up_write(&shrinker_rwsem);
> +}
> +#endif
> +
> static inline int do_shrinker_shrink(struct shrinker *shrinker,
> struct shrink_control *sc,
> unsigned long nr_to_scan)
> @@ -234,6 +271,18 @@ static inline int do_shrinker_shrink(struct shrinker *shrinker,
> }
>
> #define SHRINK_BATCH 128
> +
> +static inline struct list_head
> +*get_shrinker_list(struct shrink_control *shrink)
> +{
> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
> + if (shrink->memcg)
> + return &shrinker_memcg_list;
> + else
> +#endif
> + return &shrinker_list;
> +}
> +
> /*
> * Call the shrink functions to age shrinkable caches
> *
> @@ -259,6 +308,9 @@ unsigned long shrink_slab(struct shrink_control *shrink,
> {
> struct shrinker *shrinker;
> unsigned long ret = 0;
> + struct list_head *slist;
> +
> + slist = get_shrinker_list(shrink);
>
> if (nr_pages_scanned == 0)
> nr_pages_scanned = SWAP_CLUSTER_MAX;
> @@ -269,7 +321,7 @@ unsigned long shrink_slab(struct shrink_control *shrink,
> goto out;
> }
>
> - list_for_each_entry(shrinker, &shrinker_list, list) {
> + list_for_each_entry(shrinker, slist, list) {
> unsigned long long delta;
> long total_scan;
> long max_pass;
> @@ -2351,9 +2403,9 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
>
> /*
> * Don't shrink slabs when reclaiming memory from
> - * over limit cgroups
> + * over limit cgroups, if kernel memory is controlled independently
> */
> - if (global_reclaim(sc)) {
> + if (!global_slab_reclaim(sc)) {
> unsigned long lru_pages = 0;
> for_each_zone_zonelist(zone, z, zonelist,
> gfp_zone(sc->gfp_mask)) {
> @@ -2362,8 +2414,10 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
>
> lru_pages += zone_reclaimable_pages(zone);
> }
> + shrink->memcg = sc->target_mem_cgroup;
>
> shrink_slab(shrink, sc->nr_scanned, lru_pages);
> +
> if (reclaim_state) {
> sc->nr_reclaimed += reclaim_state->reclaimed_slab;
> reclaim_state->reclaimed_slab = 0;
> --
> 1.7.7.6
>
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