Multiple Sequential Reader vs Random Reader =============================================== Vanilla CFQ ----------------------------------- [Multiple Sequential Reader] [Random Reader] nr Agg-bandw Max-latency Agg-iops nr Agg-bandw Max-latency Agg-iops 1 13650KB/s 27614 usec 3412 1 22KB/s 227 msec 5 2 12101KB/s 568K usec 3024 1 10KB/s 457 msec 2 4 13107KB/s 322K usec 3275 1 6KB/s 841 msec 1 8 12960KB/s 829K usec 3237 1 13KB/s 1628 msec 3 16 13833KB/s 1629K usec 3452 1 10KB/s 3236 msec 2 32 13704KB/s 3389K usec 3413 1 6KB/s 3238 msec 1 IO scheduler controller + CFQ ----------------------------------- [Multiple Sequential Reader] [Random Reader] nr Agg-bandw Max-latency Agg-iops nr Agg-bandw Max-latency Agg-iops 1 5587KB/s 126K usec 1396 1 223KB/s 126K usec 55 2 4549KB/s 349K usec 1137 1 224KB/s 176K usec 56 4 5121KB/s 775K usec 1278 1 222KB/s 189K usec 55 8 6368KB/s 1680K usec 1587 1 223KB/s 142K usec 55 16 6455KB/s 3343K usec 1604 1 219KB/s 165K usec 54 32 6001KB/s 6957K usec 1482 1 220KB/s 504K usec 55 dm-ioaband + CFQ ----------------------------------- [Multiple Sequential Reader] [Random Reader] nr Agg-bandw Max-latency Agg-iops nr Agg-bandw Max-latency Agg-iops 1 12218KB/s 34608 usec 3054 1 39KB/s 218K usec 9 2 11980KB/s 135K usec 2994 1 12KB/s 424 msec 3 4 12258KB/s 604K usec 3063 1 7KB/s 811 msec 1 8 10111KB/s 835K usec 2525 1 66KB/s 692K usec 16 16 11426KB/s 1387K usec 2848 1 30KB/s 2670K usec 7 32 9318KB/s 2729K usec 2313 1 80KB/s 2413K usec 20 io-throttle + CFQ ----------------------------------- BW limit group1=10 MB/s BW limit group2=10 MB/s [Multiple Sequential Reader] [Random Reader] nr Agg-bandw Max-latency Agg-iops nr Agg-bandw Max-latency Agg-iops 1 8007KB/s 20275 usec 2001 1 37KB/s 217K usec 9 2 7661KB/s 122K usec 1914 1 16KB/s 441 msec 4 4 7672KB/s 611K usec 1916 1 9KB/s 927 msec 2 8 7507KB/s 849K usec 1874 1 21KB/s 1020 msec 5 16 7959KB/s 1679K usec 1983 1 13KB/s 2926 msec 3 32 7864KB/s 3446K usec 1952 1 8KB/s 3439 msec 2 BW limit group1=5 MB/s BW limit group2=5 MB/s [Multiple Sequential Reader] [Random Reader] nr Agg-bandw Max-latency Agg-iops nr Agg-bandw Max-latency Agg-iops 1 4576KB/s 21095 usec 1144 1 57KB/s 219K usec 14 2 4372KB/s 132K usec 1093 1 37KB/s 431K usec 9 4 4449KB/s 324K usec 1111 1 26KB/s 835 msec 6 8 4109KB/s 833K usec 1024 1 30KB/s 1625K usec 7 16 4605KB/s 1641K usec 1141 1 129KB/s 3236K usec 32 32 4269KB/s 3236K usec 1051 1 8KB/s 3235 msec 2