Systems and methods are directed to managing access to a shared memory. A request received at a memory controller, for access to the shared memory from a client of one or more clients configured to access the shared memory, is placed in at least one queue in the memory controller. A series of one or more timeout values is assigned to the request, based, at least in part on a priority associated with the client which generated the request. The priority may be fixed or based on a Quality-of-Service (QoS) class of the client. A timer is incremented while the request remains in the first queue. As the timer traverses each one of the one or more timeout values in the series, a criticality level of the request is incremented. A request with a higher criticality level may be prioritized for servicing over a request with a lower criticality level.