Overview
In the Tomasulo's Algorithm (used in most out-of-order CPUs), reservation stations are located at the input of each execution unit. They allow the CPU to 'dispatch' an instruction even if its data isn't ready yet.
Operation
- Issue: Instruction is sent to a reservation station.
- Wait: The instruction waits in the station, 'listening' for its required data to be produced by other units.
- Execute: Once all operands are available, the instruction is sent to the execution unit.
Benefit
Decouples the decoding of instructions from their execution, allowing the CPU to keep working even if some instructions are stalled waiting for data from memory.