Multiple Random Reader vs Sequential Reader =============================================== Vanilla CFQ ----------------------------------- [Multiple Random Reader] [Sequential Reader] nr Agg-bandw Max-latency Agg-iops nr Agg-bandw Max-latency Agg-iops 1 22KB/s 691 msec 5 1 13519KB/s 468K usec 3379 2 297KB/s 244K usec 74 1 12380KB/s 31675 usec 3095 4 638KB/s 249K usec 158 1 10860KB/s 36715 usec 2715 8 310KB/s 1856 msec 74 1 1292KB/s 990K usec 323 16 877KB/s 762K usec 210 1 3905KB/s 506K usec 976 32 951KB/s 2655 msec 221 1 1109KB/s 1910K usec 277 IO scheduler controller + CFQ ----------------------------------- [Multiple Random Reader] [Sequential Reader] nr Agg-bandw Max-latency Agg-iops nr Agg-bandw Max-latency Agg-iops 1 223KB/s 132K usec 55 1 5551KB/s 129K usec 1387 2 190KB/s 154K usec 46 1 5718KB/s 122K usec 1429 4 445KB/s 208K usec 111 1 5909KB/s 116K usec 1477 8 158KB/s 2820 msec 36 1 5445KB/s 168K usec 1361 16 145KB/s 5963 msec 28 1 5418KB/s 164K usec 1354 32 139KB/s 12762 msec 23 1 5398KB/s 175K usec 1349 dm-ioaband + CFQ ----------------------------------- [Multiple Random Reader] [Sequential Reader] nr Agg-bandw Max-latency Agg-iops nr Agg-bandw Max-latency Agg-iops 1 43KB/s 182K usec 10 1 14475KB/s 25559 usec 3618 2 519KB/s 138K usec 129 1 14304KB/s 26258 usec 3576 4 968KB/s 497K usec 241 1 13189KB/s 424K usec 3297 8 1418KB/s 604K usec 349 1 1593KB/s 2970K usec 398 16 1473KB/s 263K usec 361 1 1889KB/s 2099K usec 472 32 1172KB/s 1656K usec 282 1 1784KB/s 1165K usec 446 io-throttle + CFQ ----------------------------------- BW limit group1=10 MB/s BW limit group2=10 MB/s [Multiple Random Reader] [Sequential Reader] nr Agg-bandw Max-latency Agg-iops nr Agg-bandw Max-latency Agg-iops 1 36KB/s 218K usec 9 1 8006KB/s 20529 usec 2001 2 360KB/s 228K usec 89 1 7475KB/s 33665 usec 1868 4 699KB/s 262K usec 173 1 6800KB/s 46224 usec 1700 8 573KB/s 1800K usec 139 1 2835KB/s 885K usec 708 16 294KB/s 3590 msec 68 1 437KB/s 1855K usec 109 32 980KB/s 2861K usec 230 1 1145KB/s 1952K usec 286