Abstract: A method and system for providing quality of service to a plurality of hosts accessing a common resource is described. According to one embodiment, a plurality of IO requests is received from clients executing as software entities on one of the hosts. An IO request queue for each client is separately managed, and an issue queue is populated based on contents of the IO request queues. When a host issue queue is not full, a new IO request is entered into the host issue queue and is issued to the common resource. A current average latency observed at the host is calculated, and an adjusted window size is calculated at least in part based on the current average latency. The window size of the issue queue is adjusted according to the calculated window size.

Abstract: A method for providing quality of service to a plurality of hosts accessing a common resource is described. The common resource may be a middle-tier or back-end server. A client IO request is received at one host of the plurality of hosts from one of a plurality clients executing as software entities on respective hosts. The host determines whether an issue queue is full. The IO request is issued to the common resource when the issue queue is not full. A current average latency observed at the host and an adjusted window size is calculated, based at least in part on the current average latency. The issue queue is resized to correspond with the adjusted window size.

Abstract: To schedule workloads of requesters of a shared storage resource, a scheduler specifies relative fairness for the requesters of the shared storage resource. In response to the workloads of the requesters, the scheduler modifies performance of the scheduler to deviate from the specified relative fairness to improve input/output (I/O) efficiency in processing the workloads at the shared storage resource.