From c00813cdd4b11807302b45edb527f48b91120f5e Mon Sep 17 00:00:00 2001 From: Jordan Henderson Date: Wed, 23 Feb 2022 21:31:58 -0600 Subject: [PATCH] Add RELEASE.txt note for parallel compression improvements --- release_docs/RELEASE.txt | 40 +++++++++++++++++++++++++++++++++++++++- 1 file changed, 39 insertions(+), 1 deletion(-) diff --git a/release_docs/RELEASE.txt b/release_docs/RELEASE.txt index f68a7fed4f2..365d7b891fc 100644 --- a/release_docs/RELEASE.txt +++ b/release_docs/RELEASE.txt @@ -874,8 +874,46 @@ New Features Parallel Library: ----------------- - - + - Several improvements to parallel compression feature, including: + + * Improved support for collective I/O (for both writes and reads) + + * Significant reduction of memory usage for the feature as a whole + + * Reduction of copying of application data buffers passed to H5Dwrite + + * Addition of support for incremental file space allocation for filtered + datasets created in parallel. Incremental file space allocation is the + default for these types of datasets (early file space allocation is + also still supported), while early file space allocation is still the + default (and only supported allocation time) for unfiltered datasets + created in parallel. Incremental file space allocation should help with + parallel HDF5 applications that wish to use fill values on filtered + datasets, but would typically avoid doing so since dataset creation in + parallel would often take an excessive amount of time. Since these + datasets previously used early file space allocation, HDF5 would + allocate space for and write fill values to every chunk in the dataset + at creation time, leading to noticeable overhead. Instead, with + incremental file space allocation, allocation of file space for chunks + and writing of fill values to those chunks will be delayed until each + individual chunk is initially written to. + + * Addition of support for HDF5's "don't filter partial edge chunks" flag + (https://portal.hdfgroup.org/display/HDF5/H5P_SET_CHUNK_OPTS) + + * Addition of proper support for HDF5 fill values with the feature + + * Addition of 'H5_HAVE_PARALLEL_FILTERED_WRITES' macro to H5pubconf.h + so HDF5 applications can determine at compile-time whether the feature + is available + + * Addition of simple examples (ph5_filtered_writes.c and + ph5_filtered_writes_no_sel.c) under examples directory to demonstrate + usage of the feature + + * Improved coverage of regression testing for the feature + (JTH - 2022/2/23) Fortran Library: ----------------