Re: [PATCH] vmscan: Stop kswapd waiting on congestion when the minwatermark is not being met

From: Rik van Riel
Date: Fri Nov 13 2009 - 13:38:39 EST


On 11/13/2009 01:15 PM, Mel Gorman wrote:
If reclaim fails to make sufficient progress, the priority is raised.
Once the priority is higher, kswapd starts waiting on congestion. However,
if the zone is below the min watermark then kswapd needs to continue working
without delay as there is a danger of an increased rate of GFP_ATOMIC
allocation failure.

This patch changes the conditions under which kswapd waits on
congestion by only going to sleep if the min watermarks are being met.


diff --git a/mm/vmstat.c b/mm/vmstat.c
index 90b11e4..bc09547 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -685,6 +685,7 @@ static const char * const vmstat_text[] = {
"kswapd_inodesteal",
"kswapd_slept_prematurely_fast",
"kswapd_slept_prematurely_slow",
+ "kswapd_no_congestion_wait",

Perhaps better named "kswapd_skip_congestion_wait" ?

Other than that, the patch looks good to me.

Reviewed-by: Rik van Riel <riel@xxxxxxxxxx>

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