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mm: kswapd: use the classzone idx that kswapd was using for sleeping_prematurely() 

When kswapd is woken up for a high-order allocation, it takes account of
the highest usable zone by the caller (the classzone idx).  During
allocation, this index is used to select the lowmem_reserve[] that should
be applied to the watermark calculation in zone_watermark_ok().

When balancing a node, kswapd considers the highest unbalanced zone to be
the classzone index.  This will always be at least be the callers
classzone_idx and can be higher.  However, sleeping_prematurely() always
considers the lowest zone (e.g.  ZONE_DMA) to be the classzone index.
This means that sleeping_prematurely() can consider a zone to be balanced
that is unusable by the allocation request that originally woke kswapd.
This patch changes sleeping_prematurely() to use a classzone_idx matching
the value it used in balance_pgdat().

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Reviewed-by: Eric B Munson <emunson@mgebm.net>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
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 15:46:26 -08:00 committed by Linus Torvalds
parent 355b09c47a
commit dc83edd941
1 changed files with 16 additions and 13 deletions
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29
mm/vmscan.c
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@ -2227,7 +2227,8 @@ static bool pgdat_balanced(pg_data_t *pgdat, unsigned long balanced_pages,
}
/* is kswapd sleeping prematurely? */
static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining)
static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining,
int classzone_idx)
{
int i;
unsigned long balanced = 0;
@ -2235,7 +2236,7 @@ static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining)
/* If a direct reclaimer woke kswapd within HZ/10, it's premature */
if (remaining)
return 1;
return true;
/* Check the watermark levels */
for (i = 0; i < pgdat->nr_zones; i++) {
@ -2256,7 +2257,7 @@ static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining)
}
if (!zone_watermark_ok_safe(zone, order, high_wmark_pages(zone),
0, 0))
classzone_idx, 0))
all_zones_ok = false;
else
balanced += zone->present_pages;
@ -2268,7 +2269,7 @@ static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining)
* must be balanced
*/
if (order)
return pgdat_balanced(pgdat, balanced, 0);
return pgdat_balanced(pgdat, balanced, classzone_idx);
else
return !all_zones_ok;
}
@ -2295,7 +2296,7 @@ static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining)
* of pages is balanced across the zones.
*/
static unsigned long balance_pgdat(pg_data_t *pgdat, int order,
int classzone_idx)
int *classzone_idx)
{
int all_zones_ok;
unsigned long balanced;
@ -2358,6 +2359,7 @@ loop_again:
if (!zone_watermark_ok_safe(zone, order,
high_wmark_pages(zone), 0, 0)) {
end_zone = i;
*classzone_idx = i;
break;
}
}
@ -2451,12 +2453,12 @@ loop_again:
* spectulatively avoid congestion waits
*/
zone_clear_flag(zone, ZONE_CONGESTED);
if (i <= classzone_idx)
if (i <= *classzone_idx)
balanced += zone->present_pages;
}
}
if (all_zones_ok || (order && pgdat_balanced(pgdat, balanced, classzone_idx)))
if (all_zones_ok || (order && pgdat_balanced(pgdat, balanced, *classzone_idx)))
break; /* kswapd: all done */
/*
* OK, kswapd is getting into trouble. Take a nap, then take
@ -2485,7 +2487,7 @@ out:
* high-order: Balanced zones must make up at least 25% of the node
* for the node to be balanced
*/
if (!(all_zones_ok || (order && pgdat_balanced(pgdat, balanced, classzone_idx)))) {
if (!(all_zones_ok || (order && pgdat_balanced(pgdat, balanced, *classzone_idx)))) {
cond_resched();
try_to_freeze();
@ -2546,10 +2548,11 @@ out:
* if another caller entered the allocator slow path while kswapd
* was awake, order will remain at the higher level
*/
*classzone_idx = end_zone;
return order;
}
static void kswapd_try_to_sleep(pg_data_t *pgdat, int order)
static void kswapd_try_to_sleep(pg_data_t *pgdat, int order, int classzone_idx)
{
long remaining = 0;
DEFINE_WAIT(wait);
@ -2560,7 +2563,7 @@ static void kswapd_try_to_sleep(pg_data_t *pgdat, int order)
prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
/* Try to sleep for a short interval */
if (!sleeping_prematurely(pgdat, order, remaining)) {
if (!sleeping_prematurely(pgdat, order, remaining, classzone_idx)) {
remaining = schedule_timeout(HZ/10);
finish_wait(&pgdat->kswapd_wait, &wait);
prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
@ -2570,7 +2573,7 @@ static void kswapd_try_to_sleep(pg_data_t *pgdat, int order)
* After a short sleep, check if it was a premature sleep. If not, then
* go fully to sleep until explicitly woken up.
*/
if (!sleeping_prematurely(pgdat, order, remaining)) {
if (!sleeping_prematurely(pgdat, order, remaining, classzone_idx)) {
trace_mm_vmscan_kswapd_sleep(pgdat->node_id);
/*
@ -2658,7 +2661,7 @@ static int kswapd(void *p)
order = new_order;
classzone_idx = new_classzone_idx;
} else {
kswapd_try_to_sleep(pgdat, order);
kswapd_try_to_sleep(pgdat, order, classzone_idx);
order = pgdat->kswapd_max_order;
classzone_idx = pgdat->classzone_idx;
pgdat->kswapd_max_order = 0;
@ -2675,7 +2678,7 @@ static int kswapd(void *p)
*/
if (!ret) {
trace_mm_vmscan_kswapd_wake(pgdat->node_id, order);
order = balance_pgdat(pgdat, order, classzone_idx);
order = balance_pgdat(pgdat, order, &classzone_idx);
}
}
return 0;