Commit 97dd552e authored by Waiman Long's avatar Waiman Long Committed by Thomas Gleixner
Browse files

debugobjects: Scale thresholds with # of CPUs 



On a large SMP systems with hundreds of CPUs, the current thresholds
for allocating and freeing debug objects (256 and 1024 respectively)
may not work well. This can cause a lot of needless calls to
kmem_aloc() and kmem_free() on those systems.

To alleviate this thrashing problem, the object freeing threshold
is now increased to "1024 + # of CPUs * 32". Whereas the object
allocation threshold is increased to "256 + # of CPUs * 4". That
should make the debug objects subsystem scale better with the number
of CPUs available in the system.

Signed-off-by: default avatarWaiman Long <longman@redhat.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: "Du Changbin" <changbin.du@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jan Stancek <jstancek@redhat.com>
Link: http://lkml.kernel.org/r/1483647425-4135-3-git-send-email-longman@redhat.com


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent c4b73aab

lib/debugobjects.c

+15 −5
Original line number Diff line number Diff line
@@ -52,7 +52,10 @@ static int debug_objects_fixups __read_mostly; 
static int			debug_objects_warnings __read_mostly;

static int			debug_objects_enabled __read_mostly

				= CONFIG_DEBUG_OBJECTS_ENABLE_DEFAULT;



static int			debug_objects_pool_size __read_mostly

				= ODEBUG_POOL_SIZE;

static int			debug_objects_pool_min_level __read_mostly

				= ODEBUG_POOL_MIN_LEVEL;

static struct debug_obj_descr	*descr_test  __read_mostly;



/*
@@ -94,13 +97,13 @@ static void fill_pool(void) 
	struct debug_obj *new;

	unsigned long flags;



	if (likely(obj_pool_free >= ODEBUG_POOL_MIN_LEVEL))

	if (likely(obj_pool_free >= debug_objects_pool_min_level))

		return;



	if (unlikely(!obj_cache))

		return;



	while (obj_pool_free < ODEBUG_POOL_MIN_LEVEL) {

	while (obj_pool_free < debug_objects_pool_min_level) {



		new = kmem_cache_zalloc(obj_cache, gfp);

		if (!new)
@@ -176,7 +179,7 @@ static void free_obj_work(struct work_struct *work) 
	unsigned long flags;



	raw_spin_lock_irqsave(&pool_lock, flags);

	while (obj_pool_free > ODEBUG_POOL_SIZE) {

	while (obj_pool_free > debug_objects_pool_size) {

		obj = hlist_entry(obj_pool.first, typeof(*obj), node);

		hlist_del(&obj->node);

		obj_pool_free--;
@@ -206,7 +209,7 @@ static void free_object(struct debug_obj *obj) 
	 * schedule work when the pool is filled and the cache is

	 * initialized:

	 */

	if (obj_pool_free > ODEBUG_POOL_SIZE && obj_cache)

	if (obj_pool_free > debug_objects_pool_size && obj_cache)

		sched = 1;

	hlist_add_head(&obj->node, &obj_pool);

	obj_pool_free++;
@@ -1126,4 +1129,11 @@ void __init debug_objects_mem_init(void) 
		pr_warn("out of memory.\n");

	} else

		debug_objects_selftest();



	/*

	 * Increase the thresholds for allocating and freeing objects

	 * according to the number of possible CPUs available in the system.

	 */

	debug_objects_pool_size += num_possible_cpus() * 32;

	debug_objects_pool_min_level += num_possible_cpus() * 4;

}

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