How does Legion apply to FlexFLow?

[AngryBear2]

Hello, at the SysML conference in 2019, I noticed a question on the spot, you mentioned using Legion as a distributed runtime for FlexFlow, and I had some knowledge about Legion before. Could you provide more documentation or video tutorials on how Legion is used in FlexFlow, or what Legion is used for, and how it interfaces with FlexFlow?

[lockshaw]

Legion is used to coordinate distributed execution in FlexFlow: ordering of tasks, moving tensors between tasks, and partitioning computations. Currently there exist a number of calls to Legion's TaskLauncher and IndexLauncher. For example,

FlexFlow/src/ops/element_binary.cc

Lines 272 to 279 in be34be6

	IndexLauncher launcher(ELEMENTBINARY_INIT_TASK_ID,
	parallel_is,
	TaskArgument(this, sizeof(ElementBinary)),
	argmap,
	Predicate::TRUE_PRED,
	false /*must*/,
	0 /*mapper_id*/,
	outputs[0]->machine_view.hash());

In the future, #622 will be merged, which provides a more structured interface with Legion.

[AngryBear2]

Thank you so much for reading my questions and helping me.