> How does nr_to_reclaim limit the concurrency of zone reclaim? No, it doesn't prevent concurrent reclaim itself. It only prevents cuncurrent reclaim much much pages rather than SWAP_CLUSTER_MAX. note, zone reclaim uses priority 4 by default. > What happens if multiple processes are allocating from the same zone and > they all go into direct reclaim and therefore hit zone reclaim? At zone reclaim was created, 16 (1<<4) concurrent reclaim may drop all page cache because zone reclaim uses priority 4 by default. However, now we have reckaim bail out logic. So, priority 4 doesn't directly mean each zone reclaim drop 1/16 caches. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>