Multiple Random Reader vs Sequential Reader =============================================== Vanilla CFQ ----------------------------------- [Multiple Random Reader] [Sequential Reader] nr Max-bandw Min-bandw Agg-bandw Max-latency nr Agg-bandw Max-latency 1 23KB/s 23KB/s 22KB/s 691 msec 1 13519KB/s 468K usec 2 152KB/s 152KB/s 297KB/s 244K usec 1 12380KB/s 31675 usec 4 174KB/s 156KB/s 638KB/s 249K usec 1 10860KB/s 36715 usec 8 49KB/s 11KB/s 310KB/s 1856 msec 1 1292KB/s 990K usec 16 63KB/s 48KB/s 877KB/s 762K usec 1 3905KB/s 506K usec 32 35KB/s 27KB/s 951KB/s 2655 msec 1 1109KB/s 1910K usec IO scheduler controller + CFQ ----------------------------------- [Multiple Random Reader] [Sequential Reader] nr Max-bandw Min-bandw Agg-bandw Max-latency nr Agg-bandw Max-latency 1 228KB/s 228KB/s 223KB/s 132K usec 1 5551KB/s 129K usec 2 97KB/s 97KB/s 190KB/s 154K usec 1 5718KB/s 122K usec 4 115KB/s 110KB/s 445KB/s 208K usec 1 5909KB/s 116K usec 8 23KB/s 12KB/s 158KB/s 2820 msec 1 5445KB/s 168K usec 16 11KB/s 3KB/s 145KB/s 5963 msec 1 5418KB/s 164K usec 32 6KB/s 2KB/s 139KB/s 12762 msec 1 5398KB/s 175K usec dm-ioaband + CFQ ----------------------------------- [Multiple Random Reader] [Sequential Reader] nr Max-bandw Min-bandw Agg-bandw Max-latency nr Agg-bandw Max-latency 1 44KB/s 44KB/s 43KB/s 182K usec 1 14475KB/s 25559 usec 2 275KB/s 257KB/s 519KB/s 138K usec 1 14304KB/s 26258 usec 4 255KB/s 237KB/s 968KB/s 497K usec 1 13189KB/s 424K usec 8 198KB/s 170KB/s 1418KB/s 604K usec 1 1593KB/s 2970K usec 16 107KB/s 87KB/s 1473KB/s 263K usec 1 1889KB/s 2099K usec 32 41KB/s 33KB/s 1172KB/s 1656K usec 1 1784KB/s 1165K usec io-throttle + CFQ ----------------------------------- BW limit group1=10 MB/s BW limit group2=10 MB/s [Multiple Random Reader] [Sequential Reader] nr Max-bandw Min-bandw Agg-bandw Max-latency nr Agg-bandw Max-latency 1 37KB/s 37KB/s 36KB/s 218K usec 1 8006KB/s 20529 usec 2 185KB/s 183KB/s 360KB/s 228K usec 1 7475KB/s 33665 usec 4 188KB/s 171KB/s 699KB/s 262K usec 1 6800KB/s 46224 usec 8 84KB/s 51KB/s 573KB/s 1800K usec 1 2835KB/s 885K usec 16 21KB/s 9KB/s 294KB/s 3590 msec 1 437KB/s 1855K usec 32 34KB/s 27KB/s 980KB/s 2861K usec 1 1145KB/s 1952K usec