| | 1 | 0[$] Measuring (and fixing) I/O-controller throughput loss null/LWN/0000763603 70\r |
| | 2 | i [Kernel] Aug 29, 2018 21:20 UTC (Wed) (corbet)\r |
| | 3 | i\r |
| | 4 | i Many services, from web hosting and video streaming to cloud\r |
| | 5 | i storage, need to move data to and from storage. They also\r |
| | 6 | i often require that each per-client I/O flow be guaranteed a\r |
| | 7 | i non-zero amount of bandwidth and a bounded latency. An\r |
| | 8 | i expensive way to provide these guarantees is to over-provision\r |
| | 9 | i storage resources, keeping each resource underutilized, and\r |
| | 10 | i thus have plenty of bandwidth available for the few I/O flows\r |
| | 11 | i dispatched to each medium. Alternatively one can use an I/O\r |
| | 12 | i controller. Linux provides two mechanisms designed to throttle\r |
| | 13 | i some I/O streams to allow others to meet their bandwidth and\r |
| | 14 | i latency requirements. These mechanisms work, but they come at\r |
| | 15 | i a cost: a loss of as much as 80% of total available I/O\r |
| | 16 | i bandwidth. I have run some tests to demonstrate this problem;\r |
| | 17 | i some upcoming improvements to the [1]bfq I/O scheduler promise\r |
| | 18 | i to improve the situation considerably.\r |
| | 19 | i \r |
| | 20 | i \r |
| | 21 | i \r |
| | 22 | i [1] https://lwn.net/Articles/601799/\r |
| | 23 | i\r |
git://git.nikiroo.be / gofetch.git / blame_incremental