Synchronizing time across MPI ranks
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- Dominant language
- C++
- Stars
- 420
- Forks
- 80
- Avg merge
- 1d 12h
- Merged PRs (30d)
- 9
Description
I would like to compare `time.offset` across traces from different MPI ranks. I notice in the [Timestamp section](https://software.llnl.gov/Caliper/services.html#timestamp), it says:
> Note that timestamps are not synchronized between nodes in a distributed-memory program.
Is there some way to work around this? I realize that synchronizing clocks is a hopelessly complicated problem in general, but if I just wanted something like:
```
MPI_Barrier(MPI_COMM_WORLD);
caliper::reset_time();
```
Is there a way to achieve this?
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First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start with the linked Timestamp section and the existing time.offset and caliper::reset_time() entry points. Determine whether an MPI_Barrier-based synchronization mechanism can support comparing timestamps across MPI ranks; done means a documented, usable approach or a clear statement that it is unsupported.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- cpp
- Domain
- distributed-systems, hpc, performance
- Issue type
- Feature
- Difficulty
- 5/5
- Estimated time
- Over a week
- Activity status
- Stale
- Clarity
- Needs clarification
- Newbie friendliness
- 25/100