Method and system for an adapter coupled to a network via a network link is provided. The method includes using a first selectable mode and a second selectable mode to provide quality of service to a plurality of applications executed by one or more computing system. In the first selectable mode, the quality of service is based on allocating bandwidth of the network link and dynamically adjusting an initial priority assigned to a plurality of queues, each queue being associated with an application from among a plurality of applications. In the second selectable mode, the quality of service is based on a user assigning a priority to each of the plurality of applications and the adapter determines a number of input/output (I/O) requests it needs to process within a duration and then transfers information based on the determined number of I/O requests and the assigned priority.