From: Vlastimil Babka <vbabka@suse.cz>
To: Roman Gushchin <guro@fb.com>, Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>,
linux-mm@kvack.org, kernel-team@fb.com,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 13/19] mm: memcg/slab: simplify memcg cache creation
Date: Tue, 26 May 2020 12:31:29 +0200 [thread overview]
Message-ID: <9a233b26-301a-d99f-e5f3-12452c44dce7@suse.cz> (raw)
In-Reply-To: <20200422204708.2176080-14-guro@fb.com>
On 4/22/20 10:47 PM, Roman Gushchin wrote:
> Because the number of non-root kmem_caches doesn't depend on the
> number of memory cgroups anymore and is generally not very big,
> there is no more need for a dedicated workqueue.
>
> Also, as there is no more need to pass any arguments to the
> memcg_create_kmem_cache() except the root kmem_cache, it's
> possible to just embed the work structure into the kmem_cache
> and avoid the dynamic allocation of the work structure.
>
> This will also simplify the synchronization: for each root kmem_cache
> there is only one work. So there will be no more concurrent attempts
> to create a non-root kmem_cache for a root kmem_cache: the second and
> all following attempts to queue the work will fail.
>
> On the kmem_cache destruction path there is no more need to call the
> expensive flush_workqueue() and wait for all pending works to be
> finished. Instead, cancel_work_sync() can be used to cancel/wait for
> only one work.
>
> Signed-off-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
> ---
> include/linux/memcontrol.h | 1 -
> mm/memcontrol.c | 48 +-------------------------------------
> mm/slab.h | 2 ++
> mm/slab_common.c | 22 +++++++++--------
> 4 files changed, 15 insertions(+), 58 deletions(-)
>
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index 698b92d60da5..87e6da5015b3 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -1440,7 +1440,6 @@ int obj_cgroup_charge(struct obj_cgroup *objcg, gfp_t gfp, size_t size);
> void obj_cgroup_uncharge(struct obj_cgroup *objcg, size_t size);
>
> extern struct static_key_false memcg_kmem_enabled_key;
> -extern struct workqueue_struct *memcg_kmem_cache_wq;
>
> extern int memcg_nr_cache_ids;
> void memcg_get_cache_ids(void);
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 9fe2433fbe67..55fd42155a37 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -379,8 +379,6 @@ void memcg_put_cache_ids(void)
> */
> DEFINE_STATIC_KEY_FALSE(memcg_kmem_enabled_key);
> EXPORT_SYMBOL(memcg_kmem_enabled_key);
> -
> -struct workqueue_struct *memcg_kmem_cache_wq;
> #endif
>
> static int memcg_shrinker_map_size;
> @@ -2900,39 +2898,6 @@ static void memcg_free_cache_id(int id)
> ida_simple_remove(&memcg_cache_ida, id);
> }
>
> -struct memcg_kmem_cache_create_work {
> - struct kmem_cache *cachep;
> - struct work_struct work;
> -};
> -
> -static void memcg_kmem_cache_create_func(struct work_struct *w)
> -{
> - struct memcg_kmem_cache_create_work *cw =
> - container_of(w, struct memcg_kmem_cache_create_work, work);
> - struct kmem_cache *cachep = cw->cachep;
> -
> - memcg_create_kmem_cache(cachep);
> -
> - kfree(cw);
> -}
> -
> -/*
> - * Enqueue the creation of a per-memcg kmem_cache.
> - */
> -static void memcg_schedule_kmem_cache_create(struct kmem_cache *cachep)
> -{
> - struct memcg_kmem_cache_create_work *cw;
> -
> - cw = kmalloc(sizeof(*cw), GFP_NOWAIT | __GFP_NOWARN);
> - if (!cw)
> - return;
> -
> - cw->cachep = cachep;
> - INIT_WORK(&cw->work, memcg_kmem_cache_create_func);
> -
> - queue_work(memcg_kmem_cache_wq, &cw->work);
> -}
> -
> /**
> * memcg_kmem_get_cache: select memcg or root cache for allocation
> * @cachep: the original global kmem cache
> @@ -2949,7 +2914,7 @@ struct kmem_cache *memcg_kmem_get_cache(struct kmem_cache *cachep)
>
> memcg_cachep = READ_ONCE(cachep->memcg_params.memcg_cache);
> if (unlikely(!memcg_cachep)) {
> - memcg_schedule_kmem_cache_create(cachep);
> + queue_work(system_wq, &cachep->memcg_params.work);
> return cachep;
> }
>
> @@ -7122,17 +7087,6 @@ static int __init mem_cgroup_init(void)
> {
> int cpu, node;
>
> -#ifdef CONFIG_MEMCG_KMEM
> - /*
> - * Kmem cache creation is mostly done with the slab_mutex held,
> - * so use a workqueue with limited concurrency to avoid stalling
> - * all worker threads in case lots of cgroups are created and
> - * destroyed simultaneously.
> - */
> - memcg_kmem_cache_wq = alloc_workqueue("memcg_kmem_cache", 0, 1);
> - BUG_ON(!memcg_kmem_cache_wq);
> -#endif
> -
> cpuhp_setup_state_nocalls(CPUHP_MM_MEMCQ_DEAD, "mm/memctrl:dead", NULL,
> memcg_hotplug_cpu_dead);
>
> diff --git a/mm/slab.h b/mm/slab.h
> index 28c582ec997a..a4e115cb8bdc 100644
> --- a/mm/slab.h
> +++ b/mm/slab.h
> @@ -45,12 +45,14 @@ struct kmem_cache {
> * @memcg_cache: pointer to memcg kmem cache, used by all non-root memory
> * cgroups.
> * @root_caches_node: list node for slab_root_caches list.
> + * @work: work struct used to create the non-root cache.
> */
> struct memcg_cache_params {
> struct kmem_cache *root_cache;
>
> struct kmem_cache *memcg_cache;
> struct list_head __root_caches_node;
> + struct work_struct work;
> };
> #endif /* CONFIG_SLOB */
>
> diff --git a/mm/slab_common.c b/mm/slab_common.c
> index e9deaafddbb6..10aa2acb84ca 100644
> --- a/mm/slab_common.c
> +++ b/mm/slab_common.c
> @@ -132,10 +132,18 @@ int __kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t nr,
>
> LIST_HEAD(slab_root_caches);
>
> +static void memcg_kmem_cache_create_func(struct work_struct *work)
> +{
> + struct kmem_cache *cachep = container_of(work, struct kmem_cache,
> + memcg_params.work);
> + memcg_create_kmem_cache(cachep);
> +}
> +
> void slab_init_memcg_params(struct kmem_cache *s)
> {
> s->memcg_params.root_cache = NULL;
> s->memcg_params.memcg_cache = NULL;
> + INIT_WORK(&s->memcg_params.work, memcg_kmem_cache_create_func);
> }
>
> static void init_memcg_params(struct kmem_cache *s,
> @@ -584,15 +592,9 @@ static int shutdown_memcg_caches(struct kmem_cache *s)
> return 0;
> }
>
> -static void flush_memcg_workqueue(struct kmem_cache *s)
> +static void cancel_memcg_cache_creation(struct kmem_cache *s)
> {
> - /*
> - * SLAB and SLUB create memcg kmem_caches through workqueue and SLUB
> - * deactivates the memcg kmem_caches through workqueue. Make sure all
> - * previous workitems on workqueue are processed.
> - */
> - if (likely(memcg_kmem_cache_wq))
> - flush_workqueue(memcg_kmem_cache_wq);
> + cancel_work_sync(&s->memcg_params.work);
> }
> #else
> static inline int shutdown_memcg_caches(struct kmem_cache *s)
> @@ -600,7 +602,7 @@ static inline int shutdown_memcg_caches(struct kmem_cache *s)
> return 0;
> }
>
> -static inline void flush_memcg_workqueue(struct kmem_cache *s)
> +static inline void cancel_memcg_cache_creation(struct kmem_cache *s)
> {
> }
> #endif /* CONFIG_MEMCG_KMEM */
> @@ -619,7 +621,7 @@ void kmem_cache_destroy(struct kmem_cache *s)
> if (unlikely(!s))
> return;
>
> - flush_memcg_workqueue(s);
> + cancel_memcg_cache_creation(s);
>
> get_online_cpus();
> get_online_mems();
>
next prev parent reply other threads:[~2020-05-26 10:31 UTC|newest]
Thread overview: 84+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-22 20:46 [PATCH v3 00/19] The new cgroup slab memory controller Roman Gushchin
2020-04-22 20:46 ` [PATCH v3 01/19] mm: memcg: factor out memcg- and lruvec-level changes out of __mod_lruvec_state() Roman Gushchin
2020-05-07 20:33 ` Johannes Weiner
2020-05-20 10:49 ` Vlastimil Babka
2020-04-22 20:46 ` [PATCH v3 02/19] mm: memcg: prepare for byte-sized vmstat items Roman Gushchin
2020-05-07 20:34 ` Johannes Weiner
2020-05-20 11:31 ` Vlastimil Babka
2020-05-20 11:36 ` Vlastimil Babka
2020-04-22 20:46 ` [PATCH v3 03/19] mm: memcg: convert vmstat slab counters to bytes Roman Gushchin
2020-05-07 20:41 ` Johannes Weiner
2020-05-20 12:25 ` Vlastimil Babka
2020-05-20 19:26 ` Roman Gushchin
2020-05-21 9:57 ` Vlastimil Babka
2020-05-21 21:14 ` Roman Gushchin
2020-04-22 20:46 ` [PATCH v3 04/19] mm: slub: implement SLUB version of obj_to_index() Roman Gushchin
2020-04-22 23:52 ` Christopher Lameter
2020-04-23 0:05 ` Roman Gushchin
2020-04-25 2:10 ` Christopher Lameter
2020-04-25 2:46 ` Roman Gushchin
2020-04-27 16:21 ` Christopher Lameter
2020-04-27 16:46 ` Roman Gushchin
2020-04-28 17:06 ` Roman Gushchin
2020-04-28 17:45 ` Johannes Weiner
2020-04-30 16:29 ` Christopher Lameter
2020-04-30 17:15 ` Roman Gushchin
2020-05-02 23:54 ` Christopher Lameter
2020-05-04 18:29 ` Roman Gushchin
2020-05-08 21:35 ` Christopher Lameter
2020-05-13 0:57 ` Roman Gushchin
2020-05-15 21:45 ` Christopher Lameter
2020-05-15 22:12 ` Roman Gushchin
2020-05-20 9:51 ` Vlastimil Babka
2020-05-20 20:57 ` Roman Gushchin
2020-05-15 20:02 ` Roman Gushchin
2020-04-23 21:01 ` Roman Gushchin
2020-04-25 2:10 ` Christopher Lameter
2020-05-20 13:51 ` Vlastimil Babka
2020-05-20 21:00 ` Roman Gushchin
2020-05-21 11:01 ` Vlastimil Babka
2020-05-21 21:06 ` Roman Gushchin
2020-04-22 20:46 ` [PATCH v3 05/19] mm: memcontrol: decouple reference counting from page accounting Roman Gushchin
2020-04-22 20:46 ` [PATCH v3 06/19] mm: memcg/slab: obj_cgroup API Roman Gushchin
2020-05-07 21:03 ` Johannes Weiner
2020-05-07 22:26 ` Roman Gushchin
2020-05-12 22:56 ` Johannes Weiner
2020-05-15 22:01 ` Roman Gushchin
2020-04-22 20:46 ` [PATCH v3 07/19] mm: memcg/slab: allocate obj_cgroups for non-root slab pages Roman Gushchin
2020-04-23 20:20 ` Roman Gushchin
2020-05-22 18:27 ` Vlastimil Babka
2020-05-23 1:32 ` Roman Gushchin
2020-05-26 17:50 ` Roman Gushchin
2020-05-25 14:46 ` Vlastimil Babka
2020-04-22 20:46 ` [PATCH v3 08/19] mm: memcg/slab: save obj_cgroup for non-root slab objects Roman Gushchin
2020-05-25 15:07 ` Vlastimil Babka
2020-05-26 17:53 ` Roman Gushchin
2020-05-27 11:03 ` Vlastimil Babka
2020-04-22 20:46 ` [PATCH v3 09/19] mm: memcg/slab: charge individual slab objects instead of pages Roman Gushchin
2020-05-25 16:10 ` Vlastimil Babka
2020-05-26 18:04 ` Roman Gushchin
2020-04-22 20:46 ` [PATCH v3 10/19] mm: memcg/slab: deprecate memory.kmem.slabinfo Roman Gushchin
2020-05-07 21:05 ` Johannes Weiner
2020-04-22 20:47 ` [PATCH v3 11/19] mm: memcg/slab: move memcg_kmem_bypass() to memcontrol.h Roman Gushchin
2020-05-25 17:03 ` Vlastimil Babka
2020-04-22 20:47 ` [PATCH v3 12/19] mm: memcg/slab: use a single set of kmem_caches for all accounted allocations Roman Gushchin
2020-05-26 10:12 ` Vlastimil Babka
2020-04-22 20:47 ` [PATCH v3 13/19] mm: memcg/slab: simplify memcg cache creation Roman Gushchin
2020-05-26 10:31 ` Vlastimil Babka [this message]
2020-04-22 20:47 ` [PATCH v3 14/19] mm: memcg/slab: deprecate memcg_kmem_get_cache() Roman Gushchin
2020-05-26 10:34 ` Vlastimil Babka
2020-04-22 20:47 ` [PATCH v3 15/19] mm: memcg/slab: deprecate slab_root_caches Roman Gushchin
2020-05-26 10:52 ` Vlastimil Babka
2020-05-26 18:50 ` Roman Gushchin
2020-04-22 20:47 ` [PATCH v3 16/19] mm: memcg/slab: remove redundant check in memcg_accumulate_slabinfo() Roman Gushchin
2020-05-26 11:31 ` Vlastimil Babka
2020-04-22 20:47 ` [PATCH v3 17/19] mm: memcg/slab: use a single set of kmem_caches for all allocations Roman Gushchin
2020-05-26 14:55 ` Vlastimil Babka
2020-05-27 8:35 ` Jesper Dangaard Brouer
2020-04-22 20:47 ` [PATCH v3 18/19] kselftests: cgroup: add kernel memory accounting tests Roman Gushchin
2020-05-26 15:24 ` Vlastimil Babka
2020-05-26 15:45 ` Roman Gushchin
2020-05-27 17:00 ` Vlastimil Babka
2020-05-27 20:45 ` Roman Gushchin
2020-04-22 20:47 ` [PATCH v3 19/19] tools/cgroup: add memcg_slabinfo.py tool Roman Gushchin
2020-05-05 15:59 ` Tejun Heo
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