[PATCHlet] Re: kswapd @ 60-80% CPU during heavy HD i/o.

[Rik van Riel <riel@conectiva.com.br>]

On Mon, 1 May 2000, David S. Miller wrote:
> BTW, what loop are you trying to "continue;" out of here?
> 
> +			    do {
>  				if (tsk->need_resched)
>  					schedule();
>  				if ((!zone->size) || (!zone->zone_wake_kswapd))
>  					continue;
>  				do_try_to_free_pages(GFP_KSWAPD, zone);
> +			   } while (zone->free_pages < zone->pages_low &&
> +					   --count);

Ughhhhh. And the worst part is that it took me a few _days_ to
figure out ;)

Anyway, the fix for this small buglet is attached. I'll continue
working on the active/inactive lists (per pgdat!), if I haven't
sent in the active/inactive list thing for the next prepatch, it
would be nice to have this small fix applied.

regards,

Rik
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http://www.conectiva.com/		http://www.surriel.com/


--- vmscan.c.orig	Wed May  3 10:51:36 2000
+++ vmscan.c	Wed May  3 13:00:00 2000
@@ -528,15 +528,15 @@
 		pgdat = pgdat_list;
 		while (pgdat) {
 			for (i = 0; i < MAX_NR_ZONES; i++) {
-			    int count = SWAP_CLUSTER_MAX;
-			    zone = pgdat->node_zones + i;
-			    do {
-				if (tsk->need_resched)
-					schedule();
+				int count = SWAP_CLUSTER_MAX;
+				zone = pgdat->node_zones + i;
 				if ((!zone->size) || (!zone->zone_wake_kswapd))
 					continue;
-				do_try_to_free_pages(GFP_KSWAPD, zone);
-			   } while (zone->free_pages < zone->pages_low &&
+				do {
+					if (tsk->need_resched)
+						schedule();
+					do_try_to_free_pages(GFP_KSWAPD, zone);
+		 		} while (zone->free_pages < zone->pages_low &&
 					   --count);
 			}
 			pgdat = pgdat->node_next;

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