diff options
| author | Vlastimil Babka <vbabka@suse.cz> | 2016-10-07 16:57:53 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-10-07 18:46:27 -0700 |
| commit | 9861a62c335cd34a2b6b25aaaf5898e8370299ec (patch) | |
| tree | 4eb21fe16acfb2e229422de1927bfcb152781829 /mm | |
| parent | f2b8228c5f99a92bc07efd36f8dc840e0705a266 (diff) | |
mm, compaction: create compact_gap wrapper
Compaction uses a watermark gap of (2UL << order) pages at various
places and it's not immediately obvious why. Abstract it through a
compact_gap() wrapper to create a single place with a thorough
explanation.
[vbabka@suse.cz: clarify the comment of compact_gap()]
Link: http://lkml.kernel.org/r/7b6aed1f-fdf8-2063-9ff4-bbe4de712d37@suse.cz
Link: http://lkml.kernel.org/r/20160810091226.6709-9-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Tested-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/compaction.c | 7 | ||||
| -rw-r--r-- | mm/vmscan.c | 6 |
2 files changed, 6 insertions, 7 deletions
diff --git a/mm/compaction.c b/mm/compaction.c index e2618ac062a6..bbf41ee99142 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -1391,11 +1391,10 @@ static enum compact_result __compaction_suitable(struct zone *zone, int order, return COMPACT_SUCCESS; /* - * Watermarks for order-0 must be met for compaction. Note the 2UL. - * This is because during migration, copies of pages need to be - * allocated and for a short time, the footprint is higher + * Watermarks for order-0 must be met for compaction to be able to + * isolate free pages for migration targets. */ - watermark = low_wmark_pages(zone) + (2UL << order); + watermark = low_wmark_pages(zone) + compact_gap(order); if (!__zone_watermark_ok(zone, 0, watermark, classzone_idx, alloc_flags, wmark_target)) return COMPACT_SKIPPED; diff --git a/mm/vmscan.c b/mm/vmscan.c index 981fc84e7434..2a6978a07d56 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2480,7 +2480,7 @@ static inline bool should_continue_reclaim(struct pglist_data *pgdat, * If we have not reclaimed enough pages for compaction and the * inactive lists are large enough, continue reclaiming */ - pages_for_compaction = (2UL << sc->order); + pages_for_compaction = compact_gap(sc->order); inactive_lru_pages = node_page_state(pgdat, NR_INACTIVE_FILE); if (get_nr_swap_pages() > 0) inactive_lru_pages += node_page_state(pgdat, NR_INACTIVE_ANON); @@ -2612,7 +2612,7 @@ static inline bool compaction_ready(struct zone *zone, struct scan_control *sc) * there is a buffer of free pages available to give compaction * a reasonable chance of completing and allocating the page */ - watermark = high_wmark_pages(zone) + (2UL << sc->order); + watermark = high_wmark_pages(zone) + compact_gap(sc->order); watermark_ok = zone_watermark_ok_safe(zone, 0, watermark, sc->reclaim_idx); /* @@ -3169,7 +3169,7 @@ static bool kswapd_shrink_node(pg_data_t *pgdat, * excessive reclaim. Assume that a process requested a high-order * can direct reclaim/compact. */ - if (sc->order && sc->nr_reclaimed >= 2UL << sc->order) + if (sc->order && sc->nr_reclaimed >= compact_gap(sc->order)) sc->order = 0; return sc->nr_scanned >= sc->nr_to_reclaim; |