Re: [PATCH 4/4] mm: vmscan: If kswapd has been running too long, allow it to sleep

KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> · Wed, 18 May 2011 10:05:50 +0900

It would be better to put cond_resched after balance_pgdat?

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 292582c..61c45d0 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2753,6 +2753,7 @@ static int kswapd(void *p)
                 if (!ret) {
                         trace_mm_vmscan_kswapd_wake(pgdat->node_id, order);
                         order = balance_pgdat(pgdat, order,&classzone_idx);
+                       cond_resched();
                 }
         }
         return 0;

While it appears unlikely, there are bad conditions which can result
in cond_resched() being avoided.

Every reclaim priority decreasing or every shrink_zone() calling makes more
fine grained preemption. I think.


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