Systems, apparatuses, and methods for managing a number of wavefronts permitted to concurrently execute in a processing system. An apparatus includes a register file with a plurality of registers and a plurality of compute units configured to execute wavefronts. A control unit of the apparatus is configured to allow a first number of wavefronts to execute concurrently on the plurality of compute units. The control unit is configured to allow no more than a second number of wavefronts to execute concurrently on the plurality of compute units, wherein the second number is less than the first number, in response to detection that thrashing of the register file is above a threshold. The control unit is configured to detect said thrashing based at least in part on a number of registers in use by executing wavefronts that spill to memory