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.

Waiman Long committed 9 years ago

Commit 97dd5521 parent c4b73aa1 file · +15 −5Browse files

Showing the changes to lib/debugobjects.c (1 of 1 file). Show all

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lib/debugobjects.c+15−5

@@ -52,7 +52,10 @@ static int debug_objects_fixups __read_mostly; · 51 unmodified lines
52	52	static int debug_objects_warnings __read_mostly;
53	53	static int debug_objects_enabled __read_mostly
54	54	= CONFIG_DEBUG_OBJECTS_ENABLE_DEFAULT;
55		−
	55	+static int debug_objects_pool_size __read_mostly
	56	+ = ODEBUG_POOL_SIZE;
	57	+static int debug_objects_pool_min_level __read_mostly
	58	+ = ODEBUG_POOL_MIN_LEVEL;
56	59	static struct debug_obj_descr *descr_test __read_mostly;
57	60
58	61	/*
@@ -94,13 +97,13 @@ static void fill_pool(void) · 35 unmodified lines
94	97	struct debug_obj *new;
95	98	unsigned long flags;
96	99
97		− if (likely(obj_pool_free >= ODEBUG_POOL_MIN_LEVEL))
	100	+ if (likely(obj_pool_free >= debug_objects_pool_min_level))
98	101	return;
99	102
100	103	if (unlikely(!obj_cache))
101	104	return;
102	105
103		− while (obj_pool_free < ODEBUG_POOL_MIN_LEVEL) {
	106	+ while (obj_pool_free < debug_objects_pool_min_level) {
104	107
105	108	new = kmem_cache_zalloc(obj_cache, gfp);
106	109	if (!new)
@@ -176,7 +179,7 @@ static void free_obj_work(struct work_struct *work) · 69 unmodified lines
176	179	unsigned long flags;
177	180
178	181	raw_spin_lock_irqsave(&pool_lock, flags);
179		− while (obj_pool_free > ODEBUG_POOL_SIZE) {
	182	+ while (obj_pool_free > debug_objects_pool_size) {
180	183	obj = hlist_entry(obj_pool.first, typeof(*obj), node);
181	184	hlist_del(&obj->node);
182	185	obj_pool_free--;
@@ -206,7 +209,7 @@ static void free_object(struct debug_obj *obj) · 23 unmodified lines
206	209	* schedule work when the pool is filled and the cache is
207	210	* initialized:
208	211	*/
209		− if (obj_pool_free > ODEBUG_POOL_SIZE && obj_cache)
	212	+ if (obj_pool_free > debug_objects_pool_size && obj_cache)
210	213	sched = 1;
211	214	hlist_add_head(&obj->node, &obj_pool);
212	215	obj_pool_free++;
@@ -1126,4 +1129,11 @@ void __init debug_objects_mem_init(void) · 913 unmodified lines
1126	1129	pr_warn("out of memory.\n");
1127	1130	} else
1128	1131	debug_objects_selftest();
	1132	+
	1133	+ /*
	1134	+ * Increase the thresholds for allocating and freeing objects
	1135	+ * according to the number of possible CPUs available in the system.
	1136	+ */
	1137	+ debug_objects_pool_size += num_possible_cpus() * 32;
	1138	+ debug_objects_pool_min_level += num_possible_cpus() * 4;
1129	1139	}