esmf-org/esmf ESMF_8_0_1

ESMF 8.0.1

on GitHub

Overview

The 8.0.1 release fulfills two purposes: to patch a number of bugs discovered in 8.0.0, and to introduce a small selection of critical new performance features. These features were needed by operational centers in an official release that is fully backward compatible with 8.0.0. No bit-for-bit changes from ESMF regridding functions are expected in 8.0.1 relative to release 8.0.0.

One of the performance improvements introduced by ESMF 8.0.1 is message aggregation on the ESMF_VM level. This mechanism significantly improves the efficiency of inter-component data exchanges, especially in situations where there is an imbalance between the sending and receiving side. The imbalance can either be in the total number of sending vs receiving PETs, or in the timing, where the receiving PETs arrive at the exchange late, and out of sync with the sending PETs. The feature is automatically leveraged by the NUOPC level when executing the NUOPC_Connector between components on disjoint sets of PETs.

The other performance improvement added is on the ESMPy level. ESMPy now supports writing/reading of ESMF RouteHandles to/from file. This allows a user to perform the costly RouteHandle generation once, and re-use it in subsequent runs. This provides a more efficient approach to Regridding in the situation where the number of PETs does not change between runs.

Release Notes

• This release is backward compatible with ESMF 8.0.0. Two new interfaces were added to the Fortran API: ESMF_VMEpochEnter() and ESMF_VMEpochExit().
• No bit-for-bit changes are expected for this release compared to ESMF 8.0.0. This has been verified for a large number of regridding tests with Intel compilers using flags "-O2 -fp-model precise".
• No changes were made to the ESMF regrid weight generation methods and applications. The ESMF tables summarizing the ESMF regridding status are unchanged.
• The ESMF Virtual Machine (ESMF_VM) now supports message aggregation to improve performance for some very common communication patterns. Two new methods, ESMF_VMEpochEnter() and ESMF_VMEpochExit(), allow explicit use of this feature.
• The generic NUOPC_Connector automatically takes advantage of VMEpoch message aggregation when used between components on disjoint petLists.
• The ability to write/read ESMF RouteHandles to/from file was added to the ESMPy layer. This allows a user to perform the costly RouteHandle generation once, and re-use it in subsequent runs. This provides a more efficient approach to Regridding in the situation where the number of PETs does not change between runs.
• The pole_kind parameter was added to allow specification of pole behavior when creating an ESMPy Grid.

Known Bugs

• Same as ESMF_8_0_0 with the following exceptions:
  • The race condition in the ESMF_FileRegrid() method and ESMF_Regrid application has been fixed. Now if the destination grid is a multi-tile grid in GRIDSPEC MOSAIC format and the tile is distributed into multiple PETs, the regridded field is written correctly into the output file.
  • Applying the sparse matrix multiplication to cases where the local data allocation is above the 32-bit limit now works reliably.
  • The ESMF_GridCreate1PeriDim() method can now be used to create a bipole connection on the lower side.
  • The ESMF_ArrayCreate() method now succeeds when called from inside a component, requesting DE sharing.
  • The ESMF_DistGridGet() method now correctly returns "de" and "tile" information for a "localDe".
  • ESMF now correctly links against the Fortran bindings of NetCDF, even when the C and Fortran bindings of NetCDF are provided in different locations.
  • The ESMF install target now reliably works when installing ESMF into a location that is shared with other library installations.
  • The Darwin.intelclang.default build configuration now works correctly.
• Platform-specific bugs:
  • The same as ESMF_8_0_0 with the following exceptions:
    • The GNU and Intel compilers require GCC>=4.8 for C++11 support (Intel uses the GCC headers). By default ESMF now uses the C++11 standard and cannot be downgraded. If you run into build issues due to the C++11 dependency, you must make sure a GCC>=4.8 is loaded.