diff options
| -rw-r--r-- | include/linux/mmzone.h | 9 | ||||
| -rw-r--r-- | mm/vmscan.c | 31 |
2 files changed, 34 insertions, 6 deletions
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 5c76737d836b..2aaf72f7e345 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -495,6 +495,10 @@ typedef enum { ZONE_CONGESTED, /* zone has many dirty pages backed by * a congested BDI */ + ZONE_TAIL_LRU_DIRTY, /* reclaim scanning has recently found + * many dirty file pages at the tail + * of the LRU. + */ } zone_flags_t; static inline void zone_set_flag(struct zone *zone, zone_flags_t flag) @@ -517,6 +521,11 @@ static inline int zone_is_reclaim_congested(const struct zone *zone) return test_bit(ZONE_CONGESTED, &zone->flags); } +static inline int zone_is_reclaim_dirty(const struct zone *zone) +{ + return test_bit(ZONE_TAIL_LRU_DIRTY, &zone->flags); +} + static inline int zone_is_reclaim_locked(const struct zone *zone) { return test_bit(ZONE_RECLAIM_LOCKED, &zone->flags); diff --git a/mm/vmscan.c b/mm/vmscan.c index 1505c573719d..d6c916d808ba 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -676,13 +676,14 @@ static unsigned long shrink_page_list(struct list_head *page_list, struct zone *zone, struct scan_control *sc, enum ttu_flags ttu_flags, - unsigned long *ret_nr_dirty, + unsigned long *ret_nr_unqueued_dirty, unsigned long *ret_nr_writeback, bool force_reclaim) { LIST_HEAD(ret_pages); LIST_HEAD(free_pages); int pgactivate = 0; + unsigned long nr_unqueued_dirty = 0; unsigned long nr_dirty = 0; unsigned long nr_congested = 0; unsigned long nr_reclaimed = 0; @@ -808,14 +809,17 @@ static unsigned long shrink_page_list(struct list_head *page_list, if (PageDirty(page)) { nr_dirty++; + if (!PageWriteback(page)) + nr_unqueued_dirty++; + /* * Only kswapd can writeback filesystem pages to - * avoid risk of stack overflow but do not writeback - * unless under significant pressure. + * avoid risk of stack overflow but only writeback + * if many dirty pages have been encountered. */ if (page_is_file_cache(page) && (!current_is_kswapd() || - sc->priority >= DEF_PRIORITY - 2)) { + !zone_is_reclaim_dirty(zone))) { /* * Immediately reclaim when written back. * Similar in principal to deactivate_page() @@ -960,7 +964,7 @@ keep: list_splice(&ret_pages, page_list); count_vm_events(PGACTIVATE, pgactivate); mem_cgroup_uncharge_end(); - *ret_nr_dirty += nr_dirty; + *ret_nr_unqueued_dirty += nr_unqueued_dirty; *ret_nr_writeback += nr_writeback; return nr_reclaimed; } @@ -1373,6 +1377,15 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec, (nr_taken >> (DEF_PRIORITY - sc->priority))) wait_iff_congested(zone, BLK_RW_ASYNC, HZ/10); + /* + * Similarly, if many dirty pages are encountered that are not + * currently being written then flag that kswapd should start + * writing back pages. + */ + if (global_reclaim(sc) && nr_dirty && + nr_dirty >= (nr_taken >> (DEF_PRIORITY - sc->priority))) + zone_set_flag(zone, ZONE_TAIL_LRU_DIRTY); + trace_mm_vmscan_lru_shrink_inactive(zone->zone_pgdat->node_id, zone_idx(zone), nr_scanned, nr_reclaimed, @@ -2769,8 +2782,12 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order, end_zone = i; break; } else { - /* If balanced, clear the congested flag */ + /* + * If balanced, clear the dirty and congested + * flags + */ zone_clear_flag(zone, ZONE_CONGESTED); + zone_clear_flag(zone, ZONE_TAIL_LRU_DIRTY); } } @@ -2888,8 +2905,10 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order, * 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); } /* |