About the Roll back mechanism

Question

From the specification I know that when an instruction is a long-delay operation the instructions behind will be roll back, the question is how the queue of the thread recover?
for example, when encounter a store instruction, the instructions in E and D stage of the pipeline will be roll back, but the very instruction stay in the M stage, when the memory acess operation finish, how the schedualer recover the instruction queue?
Any comment is welcome, thanks

Answer 1

As I understand the documentation, a thread will roll back and (if the instruction in flight is a long latency instruction or a resource conflict) go to a Wait (not-ready-to-issue) state. The rolled-back instructions will not re-issue until their input conditions are resolved. Remember that the F and S stages (where the instructions are rolled back to) are Fetch and Thread Selection, so this is before instructions are picked from any of the threads on the core and before they are decoded. The in-flight instruction will continue from the M stage when the memory operation completes.
Also, I think the rollback condition caused a store operation only happens when the store buffer is full, not on all store operations.
Jeremy