ompi/datatype: make datatype pack thread safe #1316
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@bosilca Please take a look. This is targeted for 2.0.0. |
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Make sense, the patch is correct but sub-optimal (the packed description will be generated by all threads and then most of them will drop it). |
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@bosilca Was thinking that would be ok in this case. Using atomics avoids adding a lock to the datatype structure. I will see if I can optimize the atomics version a bit more to avoid the the duplicate description generation. |
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@regrant This is one found by the rma threading benchmarks. |
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@bosilca Ok, optimized it a bit better. Now only one thread will create the datatype description. |
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@hjelmn this looks good. Thanks for the optimization. 👍 |
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Test FAILed. |
This commit makes ompi_datatype_get_pack_description thread safe. The call is used by osc/pt2pt to send the packed description to remote peers. Before this commit if MPI_THREAD_MULTIPLE is enabled and the user uses MPI_Put, MPI_Get, etc we could hit a race where multiple threads attempt to store the packed description on the datatype. Since the code in question is not performance-critical the threading fix uses opal_atomic_* calls instead of bothering with OPAL_THREAD_*. Signed-off-by: Nathan Hjelm <[email protected]>
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ompi/datatype: make datatype pack thread safe
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This commit makes ompi_datatype_get_pack_description thread safe. The
call is used by osc/pt2pt to send the packed description to remote
peers. Before this commit if MPI_THREAD_MULTIPLE is enabled and the
user uses MPI_Put, MPI_Get, etc we could hit a race where multiple
threads attempt to store the packed description on the datatype. Since
the code in question is not performance-critical the threading fix
uses opal_atomic_* calls instead of bothering with OPAL_THREAD_*.
Signed-off-by: Nathan Hjelm [email protected]