the default control bits output by ptxas on some random ptx I made seem to be 0x003fde (why I think this is default is in the table below):
| field | #bits | val | why I think this is default | | --------------------------------------------------------------- | | reuse | 4 | 0 | can still reuse regs, we just dont give the hint to the processor that we ARE reusing it | | wait barrier mask | 6 | 3 | probably could also be 0 since the barriers for all prev instructions are 7 aka unset) | | read barrier index | 3 | 7 | unset/not making a barrier | | write barrier index | 3 | 7 | unset/not making a barrier | | yield flag | 1 | 0 | dont yield (in combination with a high stall this seems to kinda say "take as long as it takes") | stall cycles | 4 | F | take as long as it takes |
most helpful graphic I've found for understanding the encoding from this pdf
