On CUPTI document for Unified Memory counter, there is an enum value CUpti_ActivityUnifiedMemoryMigrationCause. 6.1. CUPTI Activity API — Cupti 13.0 documentation
CUPTI_ACTIVITY_UNIFIED_MEMORY_MIGRATION_CAUSE_ACCESS_COUNTERS is one of causes for page migration, which to my knowledge is a hardware counter recording memory reference requests to remote processors(GPUs, CPU) and might trigger a page migration request when it reaches a threshold (e.g. 256).
However, from the document, CUpti_ActivityUnifiedMemoryMigrationCause is only valid for H2D and D2H transfers, not including D2D.
This is valid for CUPTI_ACTIVITY_UNIFIED_MEMORY_COUNTER_KIND_BYTES_TRANSFER_HTOD and CUPTI_ACTIVITY_UNIFIED_MEMORY_COUNTER_KIND_BYTES_TRANSFER_DTOH
Does this imply that access counter works only for CPU-GPU?