Possible OSKAR output issue on macOS with OpenCL about oskar HOT 1 CLOSED

Hi, thank you for your very detailed reports! I think you may be trying to allocate too much GPU memory, which is causing things to fail (although why no error was reported is a mystery, since the error codes are definitely checked in OSKAR). Unfortunately OpenCL also has a concept of a maximum allocation size, which is often a quarter of the global memory size - although this may or may not be enforced, depending on the device and the driver.

The reason I suspect a problem with the memory usage here is because the value you have set for max_sources_per_chunk is very large (1004288), and arrays will be allocated on the GPU using this value multiplied by the number of stations (512 in this case) and the Jones matrix element size (8 bytes in this case with single precision, although it could be up to 64 bytes in double precision with full polarisation. Double precision may be needed if you're using long baselines).

There is no advantage in setting max_sources_per_chunk to be larger than the sky model, and it should rarely be set to anything larger than about 100000, but it's a tunable parameter to allow runs to be optimised for different systems. Perhaps try reducing this value to (for example) 65536 and see if you get better results.

from oskar.