I've observed that fast isolation often isolates more pages than cc->migratepages, and the excess freepages will be released back to the buddy system. So skip fast freepages isolation if enough freepages are isolated to save some CPU cycles. Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx> --- mm/compaction.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/mm/compaction.c b/mm/compaction.c index eccec84dae82..3ade4c095ed2 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -1550,6 +1550,10 @@ static void fast_isolate_freepages(struct compact_control *cc) spin_unlock_irqrestore(&cc->zone->lock, flags); + /* Skip fast search if enough freepages isolated */ + if (cc->nr_freepages >= cc->nr_migratepages) + break; + /* * Smaller scan on next order so the total scan is related * to freelist_scan_limit. -- 2.27.0
