Noop scheduler

This scheduler is useful when it has been determined that the host should not attempt to re-order requests based on the sector numbers contained therein.

Typical to performance tuning, all guidance shall be based on observed work load patterns (undermining one's ability to create simplistic rules of thumb).

For example, running an LDAP directory server may benefit from deadline's read preference and latency guarantees.

In other words, if the I/O paths are not saturated and the requests for all the workloads fail to cause an unreasonable shifting around of drive heads (which the operating system is aware of), the benefit of prioritizing one workload may create a situation where CPU time spent scheduling I/O is wasted instead of providing desired benefits.

However, most I/O workloads benefit from a certain level of requests merging, even on fast low-latency storage such as SSDs.