diff options
| -rw-r--r-- | mm/vmscan.c | 44 |
1 files changed, 39 insertions, 5 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c index 1b95e4cb195..fd47744d13b 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2119,6 +2119,42 @@ restart: throttle_vm_writeout(sc->gfp_mask); } +/* Returns true if compaction should go ahead for a high-order request */ +static inline bool compaction_ready(struct zone *zone, struct scan_control *sc) +{ + unsigned long balance_gap, watermark; + bool watermark_ok; + + /* Do not consider compaction for orders reclaim is meant to satisfy */ + if (sc->order <= PAGE_ALLOC_COSTLY_ORDER) + return false; + + /* + * Compaction takes time to run and there are potentially other + * callers using the pages just freed. Continue reclaiming until + * 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), + (zone->present_pages + KSWAPD_ZONE_BALANCE_GAP_RATIO-1) / + KSWAPD_ZONE_BALANCE_GAP_RATIO); + watermark = high_wmark_pages(zone) + balance_gap + (2UL << sc->order); + watermark_ok = zone_watermark_ok_safe(zone, 0, watermark, 0, 0); + + /* + * If compaction is deferred, reclaim up to a point where + * compaction will have a chance of success when re-enabled + */ + if (compaction_deferred(zone)) + return watermark_ok; + + /* If compaction is not ready to start, keep reclaiming */ + if (!compaction_suitable(zone, sc->order)) + return false; + + return watermark_ok; +} + /* * This is the direct reclaim path, for page-allocating processes. We only * try to reclaim pages from zones which will satisfy the caller's allocation @@ -2136,8 +2172,8 @@ restart: * scan then give up on it. * * This function returns true if a zone is being reclaimed for a costly - * high-order allocation and compaction is either ready to begin or deferred. - * This indicates to the caller that it should retry the allocation or fail. + * high-order allocation and compaction is ready to begin. This indicates to + * the caller that it should retry the allocation or fail. */ static bool shrink_zones(int priority, struct zonelist *zonelist, struct scan_control *sc) @@ -2171,9 +2207,7 @@ static bool shrink_zones(int priority, struct zonelist *zonelist, * noticable problem, like transparent huge page * allocations. */ - if (sc->order > PAGE_ALLOC_COSTLY_ORDER && - (compaction_suitable(zone, sc->order) || - compaction_deferred(zone))) { + if (compaction_ready(zone, sc)) { should_abort_reclaim = true; continue; } |