Multiple Buffered Writer vs Buffered Writer =============================================== Vanilla CFQ ----------------------------------- [Multiple Buffered Writer] [Buffered Writer] nr Agg-bandw Max-latency Agg-iops nr Agg-bandw Max-latency Agg-iops 1 67380KB/s 645K usec 1052 1 67122KB/s 567K usec 1048 2 91510KB/s 865K usec 1429 1 45118KB/s 865K usec 704 4 105MB/s 1649K usec 1675 1 26879KB/s 1643K usec 419 8 117MB/s 943K usec 1877 1 15653KB/s 766K usec 244 16 128MB/s 1174K usec 2035 1 7333KB/s 947K usec 114 32 130MB/s 1205K usec 2057 1 5142KB/s 988K usec 80 IO scheduler controller + CFQ ----------------------------------- [Multiple Buffered Writer] [Buffered Writer] nr Agg-bandw Max-latency Agg-iops nr Agg-bandw Max-latency Agg-iops 1 66972KB/s 2901K usec 1046 1 67194KB/s 2901K usec 1049 2 90936KB/s 3149K usec 1420 1 44628KB/s 2377K usec 697 4 105MB/s 1177K usec 1681 1 27584KB/s 1177K usec 431 8 114MB/s 1539K usec 1821 1 14794KB/s 783K usec 231 16 124MB/s 3177K usec 1976 1 7713KB/s 886K usec 120 32 126MB/s 1152K usec 2005 1 6465KB/s 4510K usec 101 dm-ioaband + CFQ ----------------------------------- [Multiple Buffered Writer] [Buffered Writer] nr Agg-bandw Max-latency Agg-iops nr Agg-bandw Max-latency Agg-iops 1 46643KB/s 8067K usec 728 1 45846KB/s 4950K usec 716 2 43375KB/s 14184K usec 727 1 44481KB/s 13087K usec 695 4 41669KB/s 9123K usec 688 1 42218KB/s 3652K usec 659 8 45264KB/s 19157K usec 734 1 31729KB/s 12177K usec 495 16 42866KB/s 25887K usec 700 1 40884KB/s 4593K usec 638 32 32467KB/s 29022K usec 550 1 37453KB/s 9665K usec 585 [Multiple Buffered Writer] [Buffered Writer] nr Agg-bandw Max-latency Agg-iops nr Agg-bandw Max-latency Agg-iops 1 46460KB/s 11515K usec 725 1 54637KB/s 5744K usec 853 2 48091KB/s 11436K usec 796 1 48937KB/s 2522K usec 764 4 48296KB/s 12843K usec 775 1 48026KB/s 851K usec 750 8 43467KB/s 25647K usec 694 1 49476KB/s 406K usec 773 16 28640KB/s 24128K usec 475 1 51021KB/s 2525K usec 797 32 23199KB/s 26220K usec 381 1 50644KB/s 4255K usec 791 io-throttle + CFQ ----------------------------------- BW limit group1=30 MB/s BW limit group2=30 MB/s [Multiple Buffered Writer] [Buffered Writer] nr Agg-bandw Max-latency Agg-iops nr Agg-bandw Max-latency Agg-iops 1 33070KB/s 3046K usec 516 1 25165KB/s 13248K usec 393 2 25745KB/s 9286K usec 401 1 29958KB/s 3736K usec 468 4 27145KB/s 10557K usec 422 1 30968KB/s 8356K usec 483 8 24430KB/s 12012K usec 378 1 30801KB/s 7037K usec 481 16 26632KB/s 12650K usec 409 1 31150KB/s 7173K usec 486 32 27295KB/s 14609K usec 409 1 26328KB/s 8069K usec 411