The patch titled
Subject: debugobjects: scale thresholds with # of CPUs
has been added to the -mm tree. Its filename is
debugobjects-scale-thresholds-with-of-cpus.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/debugobjects-scale-thresholds-with-of-cpus.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/debugobjects-scale-thresholds-with-of-cpus.patch
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------------------------------------------------------
From: Waiman Long <longman@xxxxxxxxxx>
Subject: 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.
Link: http://lkml.kernel.org/r/1483647425-4135-3-git-send-email-longman@xxxxxxxxxx
Signed-off-by: Waiman Long <longman@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: "Du Changbin" <changbin.du@xxxxxxxxx>
Cc: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Cc: Jan Stancek <jstancek@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/debugobjects.c | 20 +++++++++++++++-----
1 file changed, 15 insertions(+), 5 deletions(-)
diff -puN lib/debugobjects.c~debugobjects-scale-thresholds-with-of-cpus lib/debugobjects.c
--- a/lib/debugobjects.c~debugobjects-scale-thresholds-with-of-cpus
+++ a/lib/debugobjects.c
@@ -52,7 +52,10 @@ static int debug_objects_fixups __read
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_st
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
* 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;
}
_
Patches currently in -mm which might be from longman@xxxxxxxxxx are
debugobjects-track-number-of-kmem_cache_alloc-kmem_cache_free-done.patch
debugobjects-scale-thresholds-with-of-cpus.patch
debugobjects-reduce-contention-on-the-global-pool_lock.patch
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