Issue Efficiency
The fraction of cycles on which a warp scheduler issues an instruction from an eligible warp.
Issue efficiency measures how well the warp scheduler keeps the execution pipes busy by issuing instructions from eligible warps.
At 100%, every scheduler issued an instruction on every cycle, which means there was at least one eligible warp on each cycle.
Below 100%, there were cycles where every active warp was stalled, waiting on data, resources or dependencies. On those cycles the scheduler sat idle and overall instruction throughput dropped.
Related#
- Occupancy — too few warps means too few eligible candidates.
- Latency hiding — what high issue efficiency achieves.
- Scoreboard stall — a common reason warps can't issue.
- Pipe utilization — idle schedulers leave pipes under-used.