* Released under the GPL, see the file COPYING for details.
*
* Simple token based thrashing protection, using the algorithm
- * described in: http://www.cs.wm.edu/~sjiang/token.pdf
+ * described in: http://www.cse.ohio-state.edu/hpcs/WWW/HTML/publications/abs05-1.html
*
* Sep 2006, Ashwin Chaugule <ashwin.chaugule@celunite.com>
* Improved algorithm to pass token:
static DEFINE_SPINLOCK(swap_token_lock);
struct mm_struct *swap_token_mm;
-struct mem_cgroup *swap_token_memcg;
-static unsigned int global_faults;
-static unsigned int last_aging;
+static struct mem_cgroup *swap_token_memcg;
#ifdef CONFIG_CGROUP_MEM_RES_CTLR
static struct mem_cgroup *swap_token_memcg_from_mm(struct mm_struct *mm)
{
int current_interval;
unsigned int old_prio = mm->token_priority;
+ static unsigned int global_faults;
+ static unsigned int last_aging;
global_faults++;
if (!swap_token_mm)
goto replace_token;
+ /*
+ * Usually, we don't need priority aging because long interval faults
+ * makes priority decrease quickly. But there is one exception. If the
+ * token owner task is sleeping, it never make long interval faults.
+ * Thus, we need a priority aging mechanism instead. The requirements
+ * of priority aging are
+ * 1) An aging interval is reasonable enough long. Too short aging
+ * interval makes quick swap token lost and decrease performance.
+ * 2) The swap token owner task have to get priority aging even if
+ * it's under sleep.
+ */
if ((global_faults - last_aging) > TOKEN_AGING_INTERVAL) {
swap_token_mm->token_priority /= 2;
last_aging = global_faults;