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[ Identification | Description | Examples | Input parameters | Links ]
The Test_Monitor_nD_list_MPI Instrument
MPI regression test for event-list output (Monitor_nD "list all").
Identification
- Site: Tests
- Author: P. Willendrup
- Origin: DTU
- Date: October 2026
Description
Event lists recorded on several MPI nodes are gathered and written by the MPI master. This instrument controls which nodes record events, to check that list output neither hangs nor loses events when some nodes have no events, when the master has none, or when nodes flush their list buffers during TRACE a different number of times. Photons leave the source towards the monitors; the "gate" Arm absorbs them depending on the node rank and on the 'mode' parameter: mode=0: only the MPI master records events (the other nodes have none) mode=1: only the last MPI node records events (the master has none) mode=2: all nodes record all their events mode=3: no node records any event mode=4: master records all its events, node 1 every second one, other nodes one event each. Run with --bufsiz=1000000 and ncount=2.2e6 per node, the master flushes its list buffer twice during TRACE, node 1 once and the others never (a 'list all' Monitor_nD flushes its buffer when it holds --bufsiz events, if that is at least 1e6). mode=5: every node records exactly one event (single-row lists) The "events" monitor writes the list; the "count" monitor is a plain histogram (MPI_Reduce'd) interleaved with the list output. Without MPI, all modes except 3 and 5 record all events. The companion script test_mpi_lists.py runs all modes with mxrun --mpi in McCode and NeXus formats, and checks the number of listed events.
Examples
(Test cases in bold)- Test: mode=2 Detector: count_I=79566.8
Input parameters
Parameters in boldface are required; the others are optional.| Name | Unit | Description | Default |
| mode | 1 | Which MPI nodes record events, see description. | 2 |
Links
- Source code for
Test_Monitor_nD_list_MPI.instr.
[ Identification | Description | Examples | Input parameters | Links ]
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