Re: [PATCH 11/34] mm, vmscan: remove duplicate logic clearing node congestion and dirty state
From: Vlastimil Babka <hidden>
Date: 2016-07-14 09:46:06
Also in:
lkml
On 07/08/2016 11:34 AM, Mel Gorman wrote:
Reclaim may stall if there is too much dirty or congested data on a node. This was previously based on zone flags and the logic for clearing the flags is in two places. As congestion/dirty tracking is now tracked on a per-node basis, we can remove some duplicate logic. Signed-off-by: Mel Gorman <redacted> Acked-by: Hillf Danton <redacted>
I don't think it's that big a side-effect to be concerned. I would be more worried about frequently dirtying cache lines from other zone_balanced callers where, but I guess even the calls from wakeup_kswapd() rarely return true for zone_balanced(), otherwise the wakeups wouldn't have a reason to happen. Acked-by: Vlastimil Babka <redacted>
quoted hunk ↗ jump to hunk
--- mm/vmscan.c | 24 ++++++++++++------------ 1 file changed, 12 insertions(+), 12 deletions(-)diff --git a/mm/vmscan.c b/mm/vmscan.c index 01fe4708e404..8b39b903bd14 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c@@ -3008,7 +3008,17 @@ static bool zone_balanced(struct zone *zone, int order, int classzone_idx) { unsigned long mark = high_wmark_pages(zone); - return zone_watermark_ok_safe(zone, order, mark, classzone_idx); + if (!zone_watermark_ok_safe(zone, order, mark, classzone_idx)) + return false; + + /* + * If any eligible zone is balanced then the node is not considered + * to be congested or dirty + */ + clear_bit(PGDAT_CONGESTED, &zone->zone_pgdat->flags); + clear_bit(PGDAT_DIRTY, &zone->zone_pgdat->flags); + + return true; } /*@@ -3154,13 +3164,6 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx) if (!zone_balanced(zone, order, 0)) { classzone_idx = i; break; - } else { - /* - * If any eligible zone is balanced then the - * node is not considered congested or dirty. - */ - clear_bit(PGDAT_CONGESTED, &zone->zone_pgdat->flags); - clear_bit(PGDAT_DIRTY, &zone->zone_pgdat->flags); } }@@ -3219,11 +3222,8 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx) if (!populated_zone(zone)) continue; - if (zone_balanced(zone, sc.order, classzone_idx)) { - clear_bit(PGDAT_CONGESTED, &pgdat->flags); - clear_bit(PGDAT_DIRTY, &pgdat->flags); + if (zone_balanced(zone, sc.order, classzone_idx)) goto out; - } } /*
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