[PATCH RFC 16/22] block, bfq: preserve a low latency also with NCQ-capable drives

2016-02-01 Thread Paolo Valente
I/O schedulers typically allow NCQ-capable drives to prefetch I/O requests, as NCQ boosts the throughput exactly by prefetching and internally reordering requests. Unfortunately, as discussed in detail and shown experimentally in [1], this may cause fairness and latency guarantees to be violated.

[PATCH RFC 16/22] block, bfq: preserve a low latency also with NCQ-capable drives

2016-02-01 Thread Paolo Valente
I/O schedulers typically allow NCQ-capable drives to prefetch I/O requests, as NCQ boosts the throughput exactly by prefetching and internally reordering requests. Unfortunately, as discussed in detail and shown experimentally in [1], this may cause fairness and latency guarantees to be violated.