diff options
Diffstat (limited to 'mm/vmscan.c')
| -rw-r--r-- | mm/vmscan.c | 110 |
1 files changed, 54 insertions, 56 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c index a2d0c6842616..4a43c289b23a 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -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. - */ - 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. + * 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. */ - 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; } /* |