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RMA WG 02 08 2021

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Min Si edited this page Feb 8, 2021 · 1 revision

User-level threading

  • Status:
    • Wasi has studied the overhead to add ULT support into OpenSHMEM library.
    • There are minor performance differences when enabling ULT v.s., not enable ULT but not significant. Thus, overall feedback from Nick is positive
  • Regarding insufficient motivation to be added into spec (concern raised by Manju)
    • Min suggests that maybe we can propose more generic callback registration API rather than being ULT specific
    • Khaled suggests that the generic callback API might be beneficial for GPU event trigger models. But more investigation and offline discussion are necessary for a concrete concept.
  • Other comments by Nick:
    • How about add the ULT API as optional API and deprecate when more generic callback registration API is ready?
    • No active use cases of ULT in OpenSHMEM applications. How ULT is accepted by the general community?
  • Conclusion: inactive the topic in short-term. Revisit when (1) more ULT motivations are found or (2) more generic API is ready

Barrier and domain (led by Naveen)

  • shmem_barrier was deprecated and instead, quiet + sync is recommended as replacement. However, optimizations may be enabled with barrier which cannot be implemented via quiet + sync.
  • One reason to deprecate barrier was that it is unclear which context should be completed as a team may be associated with multiple contexts.
    • To address this issue, Naveen proposes a domain concept (a set of contexts collectively owned by all PEs of a team)
  • Naveen will refine the proposal and present in an upcoming WG call

Other discussion

  • We plan to regularly review/discuss each listed active topic at the WG call. Feedback can be helpful for each topic leader to prepare material/proposal drafts.
  • As usual, special discussion topic can be always added at the call.
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