From 1f0194fb641ff348a6415f56596f17dcb7e223b5 Mon Sep 17 00:00:00 2001 From: Richard Warren Date: Tue, 10 Oct 2017 09:47:22 -0400 Subject: Update the MANIFEST and release_docs/RELEASE files --- MANIFEST | 1 + release_docs/RELEASE.txt | 25 +++++++++++++++++++++++++ 2 files changed, 26 insertions(+) diff --git a/MANIFEST b/MANIFEST index fa3de21..9dca971 100644 --- a/MANIFEST +++ b/MANIFEST @@ -1244,6 +1244,7 @@ ./testpar/t_ph5basic.c ./testpar/t_pflush1.c ./testpar/t_pflush2.c +./testpar/t_pread.c ./testpar/t_prop.c ./testpar/t_shapesame.c ./testpar/t_pshutdown.c diff --git a/release_docs/RELEASE.txt b/release_docs/RELEASE.txt index d0de3ee..ed1b6cc 100644 --- a/release_docs/RELEASE.txt +++ b/release_docs/RELEASE.txt @@ -62,6 +62,31 @@ New Features Parallel Library: ----------------- + - Optimize parallel open/location of the HDF5 super-block + + Previous releases of PHDF5 allow all parallel ranks to + read the starting elements in a file to validate and process + the HDF5 super-block. As this is accomplished more or less as + a synchronous operation, a large number of processes will + likely experience a slowdown due to filesystem contention. + + As a first step in improving the startup/file-open performance, + we allow MPI rank 0 of the associated MPI communicator to locate + the base offset of the super-block and then broadcast that result + to the remaining ranks in the parallel group. Note that this + approach is utilized ONLY during file opens which employ the MPIO + file driver in HDF5 by previously having called H5Pset_fapl_mpio(). + + HDF5 parallel file operations which do not employ multiple ranks + e.g. specifiying MPI_COMM_SELF (whose MPI_Comm_size == 1) + as opposed to MPI_COMM_WORLD, will not be affected by this + optimization. Conversely, parallel file operations on subgroups + of MPI_COMM_WORLD are allowed to be run in parallel with each + subgroup operating as an independant collection of processes. + + (RAW – 2017/10/10, HDFFV-10294) + + - Large MPI-IO transfers Previous releases of PHDF5 would fail when attempting to -- cgit v0.12