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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: Waiman 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: Thomas Gleixner <tglx@linutronix.de>
zero-colors
Waiman Long 2017-01-05 15:17:04 -05:00 committed by Thomas Gleixner
parent c4b73aabd0
commit 97dd552eb2
1 changed files with 15 additions and 5 deletions
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20
lib/debugobjects.c
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@ -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;
}