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mm: vmscan: move logic from balance_pgdat() to kswapd_shrink_zone() 

balance_pgdat() is very long and some of the logic can and should be
internal to kswapd_shrink_zone().  Move it so the flow of
balance_pgdat() is marginally easier to follow.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu>
Tested-by: Zlatko Calusic <zcalusic@bitsync.net>
Cc: dormando <dormando@rydia.net>
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 2013-07-03 15:01:54 -07:00 committed by Linus Torvalds
parent b7ea3c417b
commit 7c954f6de6
1 changed files with 54 additions and 56 deletions
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110
mm/vmscan.c
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@ -2709,18 +2709,53 @@ static bool prepare_kswapd_sleep(pg_data_t *pgdat, int order, long remaining,
* This is used to determine if the scanning priority needs to be raised.
*/
static bool kswapd_shrink_zone(struct zone *zone,
int classzone_idx,
struct scan_control *sc,
unsigned long lru_pages,
unsigned long *nr_attempted)
{
unsigned long nr_slab;
int testorder = sc->order;
unsigned long balance_gap;
struct reclaim_state *reclaim_state = current->reclaim_state;
struct shrink_control shrink = {
.gfp_mask = sc->gfp_mask,
};
bool lowmem_pressure;
/* Reclaim above the high watermark. */
sc->nr_to_reclaim = max(SWAP_CLUSTER_MAX, high_wmark_pages(zone));
/*
* Kswapd reclaims only single pages with compaction enabled. Trying
* too hard to reclaim until contiguous free pages have become
* available can hurt performance by evicting too much useful data
* from memory. Do not reclaim more than needed for compaction.
*/
if (IS_ENABLED(CONFIG_COMPACTION) && sc->order &&
compaction_suitable(zone, sc->order) !=
COMPACT_SKIPPED)
testorder = 0;
/*
* We put equal pressure on every zone, unless one zone has way too
* many pages free already. The "too many pages" is defined as the
* high wmark plus a "gap" where the gap is either the low
* watermark or 1% of the zone, whichever is smaller.
*/
balance_gap = min(low_wmark_pages(zone),
(zone->managed_pages + KSWAPD_ZONE_BALANCE_GAP_RATIO-1) /
KSWAPD_ZONE_BALANCE_GAP_RATIO);
/*
* If there is no low memory pressure or the zone is balanced then no
* reclaim is necessary
*/
lowmem_pressure = (buffer_heads_over_limit && is_highmem(zone));
if (!lowmem_pressure && zone_balanced(zone, testorder,
balance_gap, classzone_idx))
return true;
shrink_zone(zone, sc);
reclaim_state->reclaimed_slab = 0;
@ -2735,6 +2770,18 @@ static bool kswapd_shrink_zone(struct zone *zone,
zone_clear_flag(zone, ZONE_WRITEBACK);
/*
* If a zone reaches its high watermark, consider it to be no longer
* congested. It's possible there are dirty pages backed by congested
* BDIs but as pressure is relieved, speculatively avoid congestion
* waits.
*/
if (!zone->all_unreclaimable &&
zone_balanced(zone, testorder, 0, classzone_idx)) {
zone_clear_flag(zone, ZONE_CONGESTED);
zone_clear_flag(zone, ZONE_TAIL_LRU_DIRTY);
}
return sc->nr_scanned >= sc->nr_to_reclaim;
}
@ -2870,8 +2917,6 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order,
*/
for (i = 0; i <= end_zone; i++) {
struct zone *zone = pgdat->node_zones + i;
int testorder;
unsigned long balance_gap;
if (!populated_zone(zone))
continue;
@ -2892,61 +2937,14 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order,
sc.nr_reclaimed += nr_soft_reclaimed;
/*
* We put equal pressure on every zone, unless
* one zone has way too many pages free
* already. The "too many pages" is defined
* as the high wmark plus a "gap" where the
* gap is either the low watermark or 1%
* of the zone, whichever is smaller.
* There should be no need to raise the scanning
* priority if enough pages are already being scanned
* that that high watermark would be met at 100%
* efficiency.
*/
balance_gap = min(low_wmark_pages(zone),
(zone->managed_pages +
KSWAPD_ZONE_BALANCE_GAP_RATIO-1) /
KSWAPD_ZONE_BALANCE_GAP_RATIO);
/*
* Kswapd reclaims only single pages with compaction
* enabled. Trying too hard to reclaim until contiguous
* free pages have become available can hurt performance
* by evicting too much useful data from memory.
* Do not reclaim more than needed for compaction.
*/
testorder = order;
if (IS_ENABLED(CONFIG_COMPACTION) && order &&
compaction_suitable(zone, order) !=
COMPACT_SKIPPED)
testorder = 0;
if ((buffer_heads_over_limit && is_highmem_idx(i)) ||
!zone_balanced(zone, testorder,
balance_gap, end_zone)) {
/*
* There should be no need to raise the
* scanning priority if enough pages are
* already being scanned that high
* watermark would be met at 100% efficiency.
*/
if (kswapd_shrink_zone(zone, &sc, lru_pages,
&nr_attempted))
raise_priority = false;
}
if (zone->all_unreclaimable) {
if (end_zone && end_zone == i)
end_zone--;
continue;
}
if (zone_balanced(zone, testorder, 0, end_zone))
/*
* If a zone reaches its high watermark,
* consider it to be no longer congested. It's
* possible there are dirty pages backed by
* congested BDIs but as pressure is relieved,
* speculatively avoid congestion waits
* or writing pages from kswapd context.
*/
zone_clear_flag(zone, ZONE_CONGESTED);
zone_clear_flag(zone, ZONE_TAIL_LRU_DIRTY);
if (kswapd_shrink_zone(zone, end_zone, &sc,
lru_pages, &nr_attempted))
raise_priority = false;
}
/*