AMReX-Astro / AMReX-Astro/Microphysics
loop over cells in order by cost to reduce divergence
Nobody has claimed this yet.
- Dominant language
- C++
- Stars
- 43
- Forks
- 46
- Avg merge
- 2d 18h
- Merged PRs (30d)
- 15
Description
It may be possible to reduce load imbalance across a warp by sorting cells based on their cost (rhs evaluations or substeps), and then looping through them based on this sorting. Then, cells with similar costs to burn are computed together across the same warp, reducing SIMD divergence.
This is mostly intended for chemistry networks, where the cost is mostly a function of density (which sets how close to equilibrium the network is).
Contributor guide
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First steps
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Research direction
No files, tests, or entry points are identified. Start by locating the chemistry-network cell loop and the rhs-evaluation or substep cost paths, then determine how cells could be ordered by cost without changing results. Done would require demonstrating reduced SIMD divergence and load imbalance on representative chemistry workloads.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- cpp
- Domain
- hpc, performance
- Issue type
- Feature
- Difficulty
- 5/5
- Estimated time
- Over a week
- Activity status
- Stale
- Clarity
- Needs clarification
- Newbie friendliness
- 25/100