llnl / llnl/libROM

Scalability break-down in `NNLSSolver` for more than 2 processors

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#272 1 comment 0 reactions 0 assignees View on GitHub

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bug
Dominant language
C++
Stars
236
Forks
47
PR merge metrics
No merged PRs in 30d

Description

Scalability test using the unit test `tests/test_NNLS` in `par-nnls` branch shows a significant slow-down when more than 2 processors are used:

| Number of processors | Time |
| :--- | ---: |
| 1 | 382ms |
| 2 | 249ms |
| 3 | 10902ms |
| 4 | 15296ms |

This test result is from a m2-chip macbook.

This issue might be related to #269 .

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  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the scalability test in tests/test_NNLS on the par-nnls branch and inspect the NNLSSolver path used for processor counts above two. Reproduce the reported timings on a comparable setup, then investigate the connection to issue #269. Done means the test no longer shows the reported slowdown as processor count increases.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp
Domain
distributed-systems, performance
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
28/100

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