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mm: kswapd: use the order that kswapd was reclaiming at for sleeping_prematurely() 

Before kswapd goes to sleep, it uses sleeping_prematurely() to check if
there was a race pushing a zone below its watermark.  If the race
happened, it stays awake.  However, balance_pgdat() can decide to reclaim
at order-0 if it decides that high-order reclaim is not working as
expected.  This information is not passed back to sleeping_prematurely().
The impact is that kswapd remains awake reclaiming pages long after it
should have gone to sleep.  This patch passes the adjusted order to
sleeping_prematurely and uses the same logic as balance_pgdat to decide if
it's ok to go to sleep.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Eric B Munson <emunson@mgebm.net>
Cc: Simon Kirby <sim@hostway.ca>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Shaohua Li <shaohua.li@intel.com>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Mel Gorman 2011-01-13 15:46:22 -08:00 committed by Linus Torvalds
parent 1741c87757
commit 0abdee2bd4
1 changed files with 11 additions and 5 deletions
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16
mm/vmscan.c
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@ -2227,7 +2227,7 @@ static bool pgdat_balanced(pg_data_t *pgdat, unsigned long balanced_pages,
}
/* is kswapd sleeping prematurely? */
static int sleeping_prematurely(pg_data_t *pgdat, int order, long remaining)
static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining)
{
int i;
unsigned long balanced = 0;
@ -2237,7 +2237,7 @@ static int sleeping_prematurely(pg_data_t *pgdat, int order, long remaining)
if (remaining)
return 1;
/* If after HZ/10, a zone is below the high mark, it's premature */
/* Check the watermark levels */
for (i = 0; i < pgdat->nr_zones; i++) {
struct zone *zone = pgdat->node_zones + i;
@ -2269,7 +2269,7 @@ static int sleeping_prematurely(pg_data_t *pgdat, int order, long remaining)
* For kswapd, balance_pgdat() will work across all this node's zones until
* they are all at high_wmark_pages(zone).
*
* Returns the number of pages which were actually freed.
* Returns the final order kswapd was reclaiming at
*
* There is special handling here for zones which are full of pinned pages.
* This can happen if the pages are all mlocked, or if they are all used by
@ -2532,7 +2532,13 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order,
}
}
return sc.nr_reclaimed;
/*
* Return the order we were reclaiming at so sleeping_prematurely()
* makes a decision on the order we were last reclaiming at. However,
* if another caller entered the allocator slow path while kswapd
* was awake, order will remain at the higher level
*/
return order;
}
static void kswapd_try_to_sleep(pg_data_t *pgdat, int order)
@ -2659,7 +2665,7 @@ static int kswapd(void *p)
*/
if (!ret) {
trace_mm_vmscan_kswapd_wake(pgdat->node_id, order);
balance_pgdat(pgdat, order, classzone_idx);
order = balance_pgdat(pgdat, order, classzone_idx);
}
}
return 0;