Agenda Notes Tuesday August 22nd 2017 2:00 PM

Date: 22 August 2017
Time: 14:00 MDT / 22:00 CET

Call-in number: 1-866-740-1260
Access Code: 4978161

Azamat Mametjanov azamat@mcs.anl.gov will be joining us to talk about:
- https://github.com/MPAS-Dev/MPAS/pull/1389 Fix data race condition in threaded halo buffer unpacking
- This is to fix some errors introduced in https://github.com/MPAS-Dev/MPAS/pull/1237/files
- Az could also talk about his efforts with gptl to measure memory usage.
Setting _FillValue attribute in output files (Xylar)
- See Issue MPAS NetCDF output does not include the _FillValue attribute
Framework modifications:
- Open framework PRs

Participants: Xylar, Mark, Azamat, Matt

PR #1389
- Fixes problems encountered on Mira, which supports 64 threads/node
- Code runs fine with one thread, fails with two or more threads
- Tried flush of just single variable, but that didn’t seem to work
- This issue just came up about a month ago
- XLF compilers only support up to OpenMP 3.1 standard
  - maybe this explains why no implicit flush with barrier?
- Are there tests in any testing suite that check threading?
Measuring memory usage with GPTL
- It would be nice to be able to record both memory usage and timing with GPTL
- However, timing with GPTL may actually be broken at the moment
- Once GPTL timers are working, Az is willing to implement memory usage
- Besides adding memory measurement calls in cores, should we add calls in some key framework routines (like I/O)?

General idea: we seem to be putting fill values into floating-point variables, but there is no attribute being added to output files

Michael will do some background checking by next telecon:
- is _FillValue a special attribute?
- can we just use PIO interface for adding this attribute along with units and description?
A related issue would be to make the time axis in MPAS output files CF compliant

Monday, 28 August 2017, 11:00 MDT

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