[PATCH] mm: yield during swap prefetching

Con Kolivas
2006-03-07T23:13:21Z

Swap prefetching doesn't use very much cpu but spends a lot of time waiting on
disk in uninterruptible sleep. This means it won't get preempted often even at
a low nice level since it is seen as sleeping most of the time. We want to
minimise its cpu impact so yield where possible.

Signed-off-by: Con Kolivas <kernel@kolivas.org>
---
mm/swap_prefetch.c | 1 +
1 file changed, 1 insertion(+)

Index: linux-2.6.15-ck5/mm/swap_prefetch.c
===================================================================
--- linux-2.6.15-ck5.orig/mm/swap_prefetch.c 2006-03-02 14:00:46.000000000 +1100
+++ linux-2.6.15-ck5/mm/swap_prefetch.c 2006-03-08 08:49:32.000000000 +1100
@@ -421,6 +421,7 @@ static enum trickle_return trickle_swap(

if (trickle_swap_cache_async(swp_entry, node) == TRICKLE_DELAY)
break;
+ yield();
}

if (sp_stat.prefetched_pages) {