llnl / llnl/UnifyFS

sync-barrier-sync in MPI I/O tests

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Dominant language
C
Stars
122
Forks
34
PR merge metrics
No merged PRs in 30d

Description

We should review our own use of MPI I/O to be sure we have the necessary sync-barrier-sync for any write/read test where a process may be trying to read data written by another process, e.g., we have a single sync here.

https://github.com/LLNL/UnifyFS/blob/fed21e57b262132939413afbd96430a9c4b157db/examples/src/testutil_rdwr.h#L249

This includes any test that queries for the file size.

Currently, I think a single ``MPI_File_sync`` call will be sufficient for UnifyFS, since that will call ``fsync()`` to flush any writes to the server. However, for proper MPI I/O usage, we should consider using the sync-barrier-sync type of construct that the MPI standard says is required.

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Research direction

Start with the single MPI_File_sync call in examples/src/testutil_rdwr.h around line 249, then search the MPI I/O tests for write/read and file-size queries. Compare each case with the required synchronization pattern and verify that all tests involving data written by another process use the appropriate sync-barrier-sync sequence.

Written by the indexing model from the issue text.

Assessment

Tech stack
c
Domain
distributed-systems, testing-qa
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
45/100

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