Resources to be used by concurrent threads in a multithreaded processor are allocated based on thread types of the threads, and thread-type-based criteria governing resource allocation decisions are dynamically modified based on feedback information indicating the degree to which various thread types are using the resource. For each of at least two thread types, an amount of the resource is reserved, and amounts currently allocated are tracked. When an allocation request for a new thread is received, the allocation is made or not based on the new thread's type, the amount of the resource reserved for that type, and the amount currently allocated to threads of that type. If, based on feedback information from the allocation decision, the amount of the resource reserved for one thread type is determined to be insufficient, the reserved amounts are modified to better meet the demand.