MANAGING MULTIPLE SPECULATIVE ASSIST THREADS AT DIFFERING CACHE LEVELS

An illustrative embodiment provides a computer-implemented process for managing multiple speculative assist threads for data pre-fetching that sends a command from an assist thread of a first processor to second processor and a memory, wherein parameters of the command specify a processor identifier of the second processor, responsive to receiving the command, reply by the second processor indicating an ability to receive a cache line that is a target of a pre-fetch, responsive to receiving the command replying by the memory indicating a capability to provide the cache line, responsive to receiving replies from the second processor and the memory, sending, by the first processor, a combined response to the second processor and the memory, wherein the combined response indicates an action, and responsive to the action indicating a transaction can continue sending the requested cache line, by the memory, to the second processor into a target cache level on the second processor.