[UR] Add support for bidirectional USM prefetching #2312
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| if (Flags == UR_USM_MIGRATION_FLAG_DEVICE_TO_HOST) { | ||
| logger::warning("USM migration from device to host is not currently " | ||
| "supported by level zero."); | ||
| return UR_RESULT_SUCCESS; | ||
| } |
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This early return is a problem for out-of-order command-lists in that it doesn't respect the command dependencies or signal dependent commands when finished.
In the else branch below think we just want to opt-out of the actual zeCommandListAppendMemoryPrefetch but keep the zeCommandListAppendWaitOnEvents and zeCommandListAppendSignalEvent commnads.
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Hey thanks for reviewing! Admittedly I'm not the most familiar with how things work in L0; would I also need to do this for source/adapters/level_zero/memory.cpp:1243?
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Yes I think that the same issue with an early return, the OutEvent output parameter won't be set and it's not respecting EventWaitList dependencies
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This PR implements the previously unimplemented
ur_usm_migration_flags_tenum, and adds the logic for prefetching for from the device to host for each implemented adapter.Note that level zero currently does not support this behavior: it remains unimplemented for now until level zero implements a way to prefetch from device to host.
Corresponding intel/llvm PR for testing: intel/llvm#16047