Choosing Problem Sizes (contd.)
- Choose problem sizes on both sides of a knee if realistic
- Critical to understand growth rate of working sets
- Also try to pick one very large size (exercises TLB misses etc.)
- Solver: first (2 subrows) usually fits, second (full partition) may or not
- Doesn’t for largest (2K) so add 4K-b-4K grid
- Add 16K as large size, so grid sizes now 256, 1K, 2K, 4K, 16K (in each dimension)
4. Use temporal locality and working sets
Fitting or not dramatically changes local traffic and artifactual comm.
E.g. Raytrace working sets are nonlocal, Ocean are local