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mm, vmscan: remove balance gap

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The balance gap was introduced to apply equal pressure to all zones when
reclaiming for a higher zone.  With node-based LRU, the need for the
balance gap is removed and the code is dead so remove it.

[vbabka@suse.cz: Also remove KSWAPD_ZONE_BALANCE_GAP_RATIO]
Link: http://lkml.kernel.org/r/1467970510-21195-9-git-send-email-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rik van Riel <riel@surriel.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 2016-07-28 15:45:46 -07:00 committed by Linus Torvalds
parent 1d82de618d
commit 31483b6ad2
2 changed files with 8 additions and 20 deletions
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9
include/linux/swap.h
View file

@ -157,15 +157,6 @@ enum {
#define SWAP_CLUSTER_MAX 32UL
#define COMPACT_CLUSTER_MAX SWAP_CLUSTER_MAX
/*
* Ratio between zone->managed_pages and the "gap" that above the per-zone
* "high_wmark". While balancing nodes, We allow kswapd to shrink zones that
* do not meet the (high_wmark + gap) watermark, even which already met the
* high_wmark, in order to provide better per-zone lru behavior. We are ok to
* spend not more than 1% of the memory for this zone balancing "gap".
*/
#define KSWAPD_ZONE_BALANCE_GAP_RATIO 100
#define SWAP_MAP_MAX 0x3e /* Max duplication count, in first swap_map */
#define SWAP_MAP_BAD 0x3f /* Note pageblock is bad, in first swap_map */
#define SWAP_HAS_CACHE 0x40 /* Flag page is cached, in first swap_map */

19
mm/vmscan.c
View file

@ -2518,7 +2518,7 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc,
*/
static inline bool compaction_ready(struct zone *zone, int order, int classzone_idx)
{
unsigned long balance_gap, watermark;
unsigned long watermark;
bool watermark_ok;
/*
@ -2527,9 +2527,7 @@ static inline bool compaction_ready(struct zone *zone, int order, int classzone_
* there is a buffer of free pages available to give compaction
* a reasonable chance of completing and allocating the page
*/
balance_gap = min(low_wmark_pages(zone), DIV_ROUND_UP(
zone->managed_pages, KSWAPD_ZONE_BALANCE_GAP_RATIO));
watermark = high_wmark_pages(zone) + balance_gap + (2UL << order);
watermark = high_wmark_pages(zone) + (2UL << order);
watermark_ok = zone_watermark_ok_safe(zone, 0, watermark, classzone_idx);
/*
@ -3000,10 +2998,9 @@ static void age_active_anon(struct pglist_data *pgdat,
} while (memcg);
}
static bool zone_balanced(struct zone *zone, int order,
unsigned long balance_gap, int classzone_idx)
static bool zone_balanced(struct zone *zone, int order, int classzone_idx)
{
unsigned long mark = high_wmark_pages(zone) + balance_gap;
unsigned long mark = high_wmark_pages(zone);
return zone_watermark_ok_safe(zone, order, mark, classzone_idx);
}
@ -3045,7 +3042,7 @@ static bool prepare_kswapd_sleep(pg_data_t *pgdat, int order, long remaining,
if (!populated_zone(zone))
continue;
if (zone_balanced(zone, order, 0, classzone_idx))
if (zone_balanced(zone, order, classzone_idx))
return true;
}
@ -3148,7 +3145,7 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx)
break;
}
if (!zone_balanced(zone, order, 0, 0)) {
if (!zone_balanced(zone, order, 0)) {
classzone_idx = i;
break;
} else {
@ -3216,7 +3213,7 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx)
if (!populated_zone(zone))
continue;
if (zone_balanced(zone, sc.order, 0, classzone_idx)) {
if (zone_balanced(zone, sc.order, classzone_idx)) {
clear_bit(PGDAT_CONGESTED, &pgdat->flags);
clear_bit(PGDAT_DIRTY, &pgdat->flags);
goto out;
@ -3427,7 +3424,7 @@ void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx)
}
if (!waitqueue_active(&pgdat->kswapd_wait))
return;
if (zone_balanced(zone, order, 0, 0))
if (zone_balanced(zone, order, 0))
return;
trace_mm_vmscan_wakeup_kswapd(pgdat->node_id, zone_idx(zone), order);