diff options
| -rw-r--r-- | mm/vmscan.c | 43 |
1 files changed, 20 insertions, 23 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c index 2a6978a..f406e6f 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2598,38 +2598,35 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc) } /* - * Returns true if compaction should go ahead for a high-order request, or - * the high-order allocation would succeed without compaction. + * Returns true if compaction should go ahead for a costly-order request, or + * the allocation would already succeed without compaction. Return false if we + * should reclaim first. */ static inline bool compaction_ready(struct zone *zone, struct scan_control *sc) { unsigned long watermark; - bool watermark_ok; + enum compact_result suitable; - /* - * 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 - */ - watermark = high_wmark_pages(zone) + compact_gap(sc->order); - watermark_ok = zone_watermark_ok_safe(zone, 0, watermark, sc->reclaim_idx); - - /* - * If compaction is deferred, reclaim up to a point where - * compaction will have a chance of success when re-enabled - */ - if (compaction_deferred(zone, sc->order)) - return watermark_ok; + suitable = compaction_suitable(zone, sc->order, 0, sc->reclaim_idx); + if (suitable == COMPACT_SUCCESS) + /* Allocation should succeed already. Don't reclaim. */ + return true; + if (suitable == COMPACT_SKIPPED) + /* Compaction cannot yet proceed. Do reclaim. */ + return false; /* - * If compaction is not ready to start and allocation is not likely - * to succeed without it, then keep reclaiming. + * Compaction is already possible, but it takes time to run and there + * are potentially other callers using the pages just freed. So proceed + * with reclaim to make a buffer of free pages available to give + * compaction a reasonable chance of completing and allocating the page. + * Note that we won't actually reclaim the whole buffer in one attempt + * as the target watermark in should_continue_reclaim() is lower. But if + * we are already above the high+gap watermark, don't reclaim at all. */ - if (compaction_suitable(zone, sc->order, 0, sc->reclaim_idx) == COMPACT_SKIPPED) - return false; + watermark = high_wmark_pages(zone) + compact_gap(sc->order); - return watermark_ok; + return zone_watermark_ok_safe(zone, 0, watermark, sc->reclaim_idx); } /* |
