6.0.x Feature List

Time Line

Target date - end CY24.

What to get done by end of Q2

• Extended Accelerator API:
  • CUDA support for IPC
  • ZE support for IPC
• Switch over to forked PRRTe Phase 1
  • Documentation Change
  • Remove Remove prte binaries
  • Remove --with-prte configure option from ompi
• BTL Self aware of accelerators
• Reduction op (and others) offload support (Joseph)
• Collectives:
  • Merge XHC if they can commit to supporting it.
  • Merge acoll once it passes CI
  • smdirect won't be merged, salvage for parts.
  • propose JSON format for tuning file
  • Remove coll/sm (tuned is OK fallback, XHC/acoll coming soon)
  • Performance testing of Luke's han alltoall pr with UCX.
• Remove:
  • GINI BTL
  • dredge_rcache
  • Remove bpfs2 components
• Big Count:
  • Collective embiggening Phase 1 (everything except *v *w collectives)

What to get done by end of Q3

• Memory Kind support:
  • Add memory-kind option
  • Return supported memory kinds
• ROMIO Refresh
• Collective embiggening Phase 2 (*v *w collectives)
• Remove:
  • Remove use TKR in MPI module for Fortran (old NAG)

List of Features planned for the 6.0.x release stream

MPI 4.0 (critical):

• Big count support
  • API level functions (in progress 1-2 months)
  • Collective embiggening (discussed at F2F, stage in none v,w functions first)
  • Changes to datatype engine/combiner support (could be a challenge)
  • ROMIO refresh
• PRRTE switch Phase 1

MPI 4.0 (tentative):

• MPI_T events (probably won't do for 6.0.x).

Accelerator support:

• extended accelerator API functionality (IPC) and conversion of the last components to use accelerator API (DONE for ROCM, not CUDA or ZE).
• level zero (ze) accelerator component (DONE basic support, IPC not implemented, Howard)
• support for MPI 4.1 memory kinds info object (assume we have PRRTE move, 1 month for basic support)
• reduction op (and others) offload support (Joseph estimates 1-2 months to get in)
• SMSC accelerator (Edgar - not sure yet about this one for 6.0.x)
  • Stream-aware datatype engine.
• BTL self issue (doesn't support accelerators currently). (Khawthar working on this)
• Datatype engine accelerator awareness(e.g. memcpy2d) (George).

What about smart pointers? Probably could not get this in to a 6.0.x.

MPI 4.1:

• implement memory allocation kind info. (see above for accelerator features)

Things to remove:

• GNI BTL - no longer have access to systems to support this (Howard)
• UDREG Rcache - no longer have access to systems that can use this (Howard)
• FS/PVFS2 an FBTL/PVFS2 - no longer have access to systems to support this (Edgar)
• coll/sm
• Remove TKR version of use mpi module. (Howard)
  • This was deferred from 4.0.x because in April/May 2018 (and then deferred again from v5.0.x in October 2018), it was discovered that:
    1. The RHEL 7.x default gcc (4.8.5) still uses the TKR mpi module
    2. The NAG compiler still uses the TKR mpi module.

Collectives:

• mca/coll: blocking reduction on accelerator (this is discussed above, Joseph)
• mca/coll: hierarchical MPI_Alltoall(v), MPI_Gatherv, MPI_Scatterv. (various orgs working on this)
• mca/coll: new algorithms (various orgs working on this)

There are quite a few open PRs related to collectives. Can some of these get merged? See notes from 2024 F2F Meeting

Random:

• Sessions - add support for UCX PML (Howard, 2-3 weeks)
• Sessions - various small fixes (Howard, 1 month)
• Atomics - can we just rely on C11 and remove some of this code? We are currently using gcc atomics for performance reasons. Joseph would like to have a wrapper for atomic types and direct load/store access.