According to the commit 215ddd66 (mm: vmscan: only read new_classzone_idx from
pgdat when reclaiming successfully) and the commit d2ebd0f6b (kswapd: avoid
unnecessary rebalance after an unsuccessful balancing), we can use a boolean
variable for replace balanced_* variables, which makes the kswapd more clarify.
Signed-off-by: Chen Yucong <sla...@gmail.com>
---
mm/vmscan.c | 29 ++++++++++++++++-------------
1 file changed, 16 insertions(+), 13 deletions(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index a8ffe4e..b0a75d1 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -3332,10 +3332,9 @@ static void kswapd_try_to_sleep(pg_data_t *pgdat, int
order, int classzone_idx)
*/
static int kswapd(void *p)
{
+ bool balance_is_successful;
unsigned long order, new_order;
- unsigned balanced_order;
int classzone_idx, new_classzone_idx;
- int balanced_classzone_idx;
pg_data_t *pgdat = (pg_data_t*)p;
struct task_struct *tsk = current;
@@ -3366,9 +3365,7 @@ static int kswapd(void *p)
set_freezable();
order = new_order = 0;
- balanced_order = 0;
classzone_idx = new_classzone_idx = pgdat->nr_zones - 1;
- balanced_classzone_idx = classzone_idx;
for ( ; ; ) {
bool ret;
@@ -3377,24 +3374,32 @@ static int kswapd(void *p)
* new request of a similar or harder type will succeed soon
* so consider going to sleep on the basis we reclaimed at
*/
- if (balanced_classzone_idx >= new_classzone_idx &&
- balanced_order == new_order) {
+ balance_is_successful = false;
+ if (classzone_idx >= new_classzone_idx && order == new_order) {
+ /*
+ * After the last balance_pgdat, if the `order' stays
+ * constant and the scanned zones are not less than
+ * specified by original classzone_idx, then the last
+ * balance_pgdat was successful.
+ */
new_order = pgdat->kswapd_max_order;
new_classzone_idx = pgdat->classzone_idx;
pgdat->kswapd_max_order = 0;
pgdat->classzone_idx = pgdat->nr_zones - 1;
+ balance_is_successful = true;
}
- if (order < new_order || classzone_idx > new_classzone_idx) {
+ if (balance_is_successful && (order < new_order ||
+ classzone_idx > new_classzone_idx)) {
/*
* Don't sleep if someone wants a larger 'order'
- * allocation or has tigher zone constraints
+ * allocation or has tighter zone constraints on the
+ * premise of the last balance_pgdat was successful.
*/
order = new_order;
classzone_idx = new_classzone_idx;
} else {
- kswapd_try_to_sleep(pgdat, balanced_order,
- balanced_classzone_idx);
+ kswapd_try_to_sleep(pgdat, order, classzone_idx);
order = pgdat->kswapd_max_order;
classzone_idx = pgdat->classzone_idx;
new_order = order;
@@ -3413,9 +3418,7 @@ static int kswapd(void *p)
*/
if (!ret) {
trace_mm_vmscan_kswapd_wake(pgdat->node_id, order);
- balanced_classzone_idx = classzone_idx;
- balanced_order = balance_pgdat(pgdat, order,
- &balanced_classzone_idx);
+ order = balance_pgdat(pgdat, order, &classzone_idx);
}
}
--
1.7.10.4
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