Mel Gorman <mgorman@xxxxxxx> writes: > The existing CFQ default target_latency results in very poor performance > for larger numbers of threads doing sequential reads. While this can be > easily described as a tuning problem for users, it is one that is tricky > to detect. This patch the default on the assumption that people with access > to expensive fast storage also know how to tune their IO scheduler. > > The following is from tiobench run on a mid-range desktop with a single > spinning disk. > > 3.16.0-rc1 3.16.0-rc1 3.0.0 > vanilla cfq600 vanilla > Mean SeqRead-MB/sec-1 121.88 ( 0.00%) 121.60 ( -0.23%) 134.59 ( 10.42%) > Mean SeqRead-MB/sec-2 101.99 ( 0.00%) 102.35 ( 0.36%) 122.59 ( 20.20%) > Mean SeqRead-MB/sec-4 97.42 ( 0.00%) 99.71 ( 2.35%) 114.78 ( 17.82%) > Mean SeqRead-MB/sec-8 83.39 ( 0.00%) 90.39 ( 8.39%) 100.14 ( 20.09%) > Mean SeqRead-MB/sec-16 68.90 ( 0.00%) 77.29 ( 12.18%) 81.64 ( 18.50%) Did you test any workloads other than this? Also, what normal workload has 8 or more threads doing sequential reads? (That's an honest question.) Cheers, Jeff -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>