From: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> Subject: mm, vmscan: remove balance gap 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@xxxxxxx: Also remove KSWAPD_ZONE_BALANCE_GAP_RATIO] Link: http://lkml.kernel.org/r/1467970510-21195-9-git-send-email-mgorman@xxxxxxxxxxxxxxxxxxx Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> Acked-by: Vlastimil Babka <vbabka@xxxxxxx> Cc: Hillf Danton <hillf.zj@xxxxxxxxxxxxxxx> Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx> Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxxxx> Cc: Minchan Kim <minchan@xxxxxxxxxx> Cc: Rik van Riel <riel@xxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/swap.h | 9 --------- mm/vmscan.c | 19 ++++++++----------- 2 files changed, 8 insertions(+), 20 deletions(-) diff -puN include/linux/swap.h~mm-vmscan-remove-balance-gap include/linux/swap.h --- a/include/linux/swap.h~mm-vmscan-remove-balance-gap +++ a/include/linux/swap.h @@ -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 */ diff -puN mm/vmscan.c~mm-vmscan-remove-balance-gap mm/vmscan.c --- a/mm/vmscan.c~mm-vmscan-remove-balance-gap +++ a/mm/vmscan.c @@ -2518,7 +2518,7 @@ static bool shrink_node(pg_data_t *pgdat */ 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(stru * 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 pglis } 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 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 *pgda 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 *pgda 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, in } 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); _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
