Several libraries and programs have been updated on hexagon. Users are encouraged to recompile their programs to get fixes and performance-increases. In particular, codes that use MPI_Bcast will see an improvement with the new xt-mpt release, see notes below.

MPI:
xt-mpt 3.1.0 -> 3.1.1

COMPILER and tools:
pgi 8.0.2 -> 8.0.3
xt-asyncpe 2.0 -> 2.1 (compiler wrapper)
java 1.6.0-7 -> 1.6.0-11

LIBRARIES:
hdf5 and hdf5-parallell 1.6.7a -> 1.8.2
netCDF 3.6.2 -> 4.0
fftw 3.1.1 -> 3.2.0
PetSC 2.3.3a -> 3.0.0
ACML 4.1.0 -> 4.2.0 (previously installed but not listed)
xt-libsci 10.3.1 -> 10.3.2 (previously installed but not listed)
libfast 1.0 -> 1.0.2 (previously installed but not listed)

NEW LIBRARIES:
netcdf-hdf5parallell 4.0 (combined netcdf-hdf5-parallell)

NEW TOOLS:
xt-lgdb 1.1 (Cray version of gdb to use for MPI debugging on XT)

NOTES FOR XT-MPT:

- MPI_Bcast has been optimized to be SMP aware and this optimization is enabled by default. The performance improvement varies depending on message size and number of ranks but improvements of between 10% and 35% for messages below 128K bytes have been observed.

- Improvements have been made to the MPICH_COLL_OPT_OFF environment variable by allowing a finer-grain switch to enable/disable the optimized collectives.
The user may now:
- Enable all of the optimized collectives (this is the default)
- Disable all the opt collectives (export MPICH_COLL_OPT_OFF=0)
- Disable a selected set of the optimized collectives by providing
a comma-separated list of the collective names
e.g. export MPICH_COLL_OPT_OFF=MPI_Allreduce,MPI_Bcast,MPI_Alltoallv
If a user chooses to disable any Cray-optimized collective, they will get the standard MPICH2 algorithm.