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Commit 17cc4dfe authored by Tejun Heo's avatar Tejun Heo Committed by Linus Torvalds
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slab: use memcg_kmem_cache_wq for slab destruction operations 

If there's contention on slab_mutex, queueing the per-cache destruction
work item on the system_wq can unnecessarily create and tie up a lot of
kworkers.

Rename memcg_kmem_cache_create_wq to memcg_kmem_cache_wq and make it
global and use that workqueue for the destruction work items too.  While
at it, convert the workqueue from an unbound workqueue to a per-cpu one
with concurrency limited to 1.  It's generally preferable to use per-cpu
workqueues and concurrency limit of 1 is safe enough.

This is suggested by Joonsoo Kim.

Link: http://lkml.kernel.org/r/20170117235411.9408-11-tj@kernel.org


Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Reported-by: default avatarJay Vana <jsvana@fb.com>
Acked-by: default avatarVladimir Davydov <vdavydov@tarantool.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 50862ce7

include/linux/memcontrol.h

+1 −0
Original line number Diff line number Diff line
@@ -830,6 +830,7 @@ void memcg_kmem_uncharge(struct page *page, int order); 


#if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB)

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);

mm/memcontrol.c

+8 −8
Original line number Diff line number Diff line
@@ -317,6 +317,8 @@ 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 /* !CONFIG_SLOB */



/**
@@ -2143,8 +2145,6 @@ struct memcg_kmem_cache_create_work { 
	struct work_struct work;

};



static struct workqueue_struct *memcg_kmem_cache_create_wq;



static void memcg_kmem_cache_create_func(struct work_struct *w)

{

	struct memcg_kmem_cache_create_work *cw =
@@ -2176,7 +2176,7 @@ static void __memcg_schedule_kmem_cache_create(struct mem_cgroup *memcg, 
	cw->cachep = cachep;

	INIT_WORK(&cw->work, memcg_kmem_cache_create_func);



	queue_work(memcg_kmem_cache_create_wq, &cw->work);

	queue_work(memcg_kmem_cache_wq, &cw->work);

}



static void memcg_schedule_kmem_cache_create(struct mem_cgroup *memcg,
@@ -5778,12 +5778,12 @@ static int __init mem_cgroup_init(void) 
#ifndef CONFIG_SLOB

	/*

	 * Kmem cache creation is mostly done with the slab_mutex held,

	 * so use a special workqueue to avoid stalling all worker

	 * threads in case lots of cgroups are created simultaneously.

	 * 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_create_wq =

		alloc_ordered_workqueue("memcg_kmem_cache_create", 0);

	BUG_ON(!memcg_kmem_cache_create_wq);

	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,

mm/slab_common.c

+1 −1
Original line number Diff line number Diff line
@@ -659,7 +659,7 @@ static void kmemcg_deactivate_rcufn(struct rcu_head *head) 
	 * initialized eariler.

	 */

	INIT_WORK(&s->memcg_params.deact_work, kmemcg_deactivate_workfn);

	schedule_work(&s->memcg_params.deact_work);

	queue_work(memcg_kmem_cache_wq, &s->memcg_params.deact_work);

}



/**