Multiple Buffered Writer vs Buffered Writer =============================================== Vanilla CFQ ----------------------------------- [Multiple Buffered Writer] [Buffered Writer] nr Max-bandw Min-bandw Agg-bandw Max-latency nr Agg-bandw Max-latency 1 68997KB/s 68997KB/s 67380KB/s 645K usec 1 67122KB/s 567K usec 2 47509KB/s 46218KB/s 91510KB/s 865K usec 1 45118KB/s 865K usec 4 28002KB/s 26906KB/s 105MB/s 1649K usec 1 26879KB/s 1643K usec 8 15985KB/s 14849KB/s 117MB/s 943K usec 1 15653KB/s 766K usec 16 11567KB/s 6881KB/s 128MB/s 1174K usec 1 7333KB/s 947K usec 32 5877KB/s 3649KB/s 130MB/s 1205K usec 1 5142KB/s 988K usec IO scheduler controller + CFQ ----------------------------------- [Multiple Buffered Writer] [Buffered Writer] nr Max-bandw Min-bandw Agg-bandw Max-latency nr Agg-bandw Max-latency 1 68580KB/s 68580KB/s 66972KB/s 2901K usec 1 67194KB/s 2901K usec 2 47419KB/s 45700KB/s 90936KB/s 3149K usec 1 44628KB/s 2377K usec 4 27825KB/s 27274KB/s 105MB/s 1177K usec 1 27584KB/s 1177K usec 8 15382KB/s 14288KB/s 114MB/s 1539K usec 1 14794KB/s 783K usec 16 9161KB/s 7592KB/s 124MB/s 3177K usec 1 7713KB/s 886K usec 32 4928KB/s 3961KB/s 126MB/s 1152K usec 1 6465KB/s 4510K usec dm-ioaband + CFQ ----------------------------------- [Multiple Buffered Writer] [Buffered Writer] nr Max-bandw Min-bandw Agg-bandw Max-latency nr Agg-bandw Max-latency 1 47762KB/s 47762KB/s 46643KB/s 8067K usec 1 45846KB/s 4950K usec 2 31549KB/s 16132KB/s 43375KB/s 14184K usec 1 44481KB/s 13087K usec 4 14870KB/s 8113KB/s 41669KB/s 9123K usec 1 42218KB/s 3652K usec 8 17481KB/s 1912KB/s 45264KB/s 19157K usec 1 31729KB/s 12177K usec 16 19636KB/s 760KB/s 42866KB/s 25887K usec 1 40884KB/s 4593K usec 32 2283KB/s 212KB/s 32467KB/s 29022K usec 1 37453KB/s 9665K usec [Multiple Buffered Writer] [Buffered Writer] nr Max-bandw Min-bandw Agg-bandw Max-latency nr Agg-bandw Max-latency 1 47575KB/s 47575KB/s 46460KB/s 11515K usec 1 54637KB/s 5744K usec 2 30187KB/s 22042KB/s 48091KB/s 11436K usec 1 48937KB/s 2522K usec 4 14525KB/s 11052KB/s 48296KB/s 12843K usec 1 48026KB/s 851K usec 8 16076KB/s 2035KB/s 43467KB/s 25647K usec 1 49476KB/s 406K usec 16 2711KB/s 733KB/s 28640KB/s 24128K usec 1 51021KB/s 2525K usec 32 1670KB/s 372KB/s 23199KB/s 26220K usec 1 50644KB/s 4255K usec io-throttle + CFQ ----------------------------------- BW limit group1=30 MB/s BW limit group2=30 MB/s [Multiple Buffered Writer] [Buffered Writer] nr Max-bandw Min-bandw Agg-bandw Max-latency nr Agg-bandw Max-latency 1 33863KB/s 33863KB/s 33070KB/s 3046K usec 1 25165KB/s 13248K usec 2 13457KB/s 12906KB/s 25745KB/s 9286K usec 1 29958KB/s 3736K usec 4 7414KB/s 6543KB/s 27145KB/s 10557K usec 1 30968KB/s 8356K usec 8 3562KB/s 2640KB/s 24430KB/s 12012K usec 1 30801KB/s 7037K usec 16 3962KB/s 881KB/s 26632KB/s 12650K usec 1 31150KB/s 7173K usec 32 3275KB/s 406KB/s 27295KB/s 14609K usec 1 26328KB/s 8069K usec