Multiple Random Writer vs Random Reader =============================================== Vanilla CFQ ----------------------------------- [Multiple Random Writer] [Random Reader] nr Agg-bandw Max-latency Agg-iops nr Agg-bandw Max-latency Agg-iops 1 62517KB/s 353K usec 976 1 190KB/s 96 msec 47 2 68899KB/s 208K usec 1075 1 76KB/s 2416 msec 19 4 60630KB/s 3746K usec 946 1 106KB/s 2308K usec 26 8 33335KB/s 2995K usec 516 1 193KB/s 2292K usec 48 16 51807KB/s 2283K usec 801 1 72KB/s 2298K usec 18 32 56882KB/s 1990K usec 874 1 35KB/s 1093 msec 8 IO scheduler controller + CFQ ----------------------------------- [Multiple Random Writer] [Random Reader] nr Agg-bandw Max-latency Agg-iops nr Agg-bandw Max-latency Agg-iops 1 19892KB/s 877K usec 310 1 255KB/s 137K usec 63 2 27964KB/s 1010K usec 436 1 228KB/s 117K usec 57 4 26775KB/s 1362K usec 417 1 221KB/s 180K usec 55 8 22007KB/s 2660K usec 341 1 250KB/s 485K usec 62 16 22384KB/s 2606K usec 344 1 254KB/s 115K usec 63 32 22404KB/s 2879K usec 332 1 266KB/s 107K usec 66 dm-ioaband + CFQ ----------------------------------- [Multiple Random Writer] [Random Reader] nr Agg-bandw Max-latency Agg-iops nr Agg-bandw Max-latency Agg-iops 1 60893KB/s 82885 usec 951 1 197KB/s 118 msec 49 2 68068KB/s 625K usec 1062 1 65KB/s 2335 msec 16 4 63662KB/s 1005K usec 992 1 69KB/s 1540 msec 17 8 39472KB/s 2037K usec 612 1 180KB/s 1479K usec 45 16 41654KB/s 820K usec 644 1 59KB/s 3350 msec 14 32 19668KB/s 2440K usec 292 1 17KB/s 4090 msec 4 io-throttle + CFQ ----------------------------------- BW limit group1=30 MB/s BW limit group2=30 MB/s [Multiple Random Writer] [Random Reader] nr Agg-bandw Max-latency Agg-iops nr Agg-bandw Max-latency Agg-iops 1 21406KB/s 1017K usec 334 1 353KB/s 432K usec 88 2 23357KB/s 1832K usec 364 1 362KB/s 177K usec 90 4 24736KB/s 1336K usec 385 1 348KB/s 425K usec 87 8 23792KB/s 2133K usec 369 1 336KB/s 146K usec 84 16 23694KB/s 2198K usec 365 1 337KB/s 115K usec 84 32 23198KB/s 2195K usec 353 1 330KB/s 192K usec 82 BW limit group1=10 MB/s BW limit group2=10 MB/s [Multiple Random Writer] [Random Reader] nr Agg-bandw Max-latency Agg-iops nr Agg-bandw Max-latency Agg-iops 1 7718KB/s 1037K usec 120 1 474KB/s 103K usec 118 2 8715KB/s 1091K usec 135 1 450KB/s 553K usec 112 4 7914KB/s 2042K usec 121 1 458KB/s 108K usec 114 8 8688KB/s 1280K usec 133 1 432KB/s 98215 usec 108 16 8668KB/s 2303K usec 129 1 426KB/s 90609 usec 106 32 8599KB/s 2557K usec 125 1 441KB/s 95283 usec 110