Prefetcher with arbitrary downstream prefetch cancelation

A digital system, comprising:

• a shared memory system for storing and retrieving data;
• a first prefetch unit for generating speculative prefetches for a first cache that is local to a first processor, wherein the first prefetch unit is arranged to receive a first set of memory commands from a first requestor that is the first processor or the first cache;
• a central memory arbiter that is arranged to receive and evaluate memory commands from the first prefetch unit to identify whether the received memory command is a speculative prefetch from the first prefetch unit, to apply a first set of arbitrary policies to the identified speculative prefetches to select one or more of the received speculative prefetches to cancel, wherein the first set of arbitrary policies is arranged to reduce memory accesses to the shared memory that is memory resource that is at a lower-level hierarchy than the first requestor;
• and to cancel the selected speculative prefetches by sending a cancelation notification of each canceled speculative prefetch to a first higher-level memory component that is local to the first processor.

An arbitration system for arbitrary cancelation of speculative prefetches in a multiprocessor system, comprising:

• a shared memory system for storing and retrieving data;
• a first prefetch unit for generating speculative prefetches for a first cache that is local to a first processor, wherein the first prefetch unit is arranged to receive a first set of memory commands from a first requestor that is the first processor or the first cache;
• a second prefetch unit for generating speculative prefetches for a second cache that is local to a second processor, wherein the second prefetch unit is arranged to receive a second set of memory commands from a second requestor that is the second processor or the second cache;
• a central memory arbiter that is arranged to evaluate speculative prefetches from the first and second prefetch units by applying a set of arbitrary policies to the speculative prefetches, to select one or more of the received speculative prefetches to cancel in response to the evaluation, and to cancel the selected speculative prefetches by sending a cancelation notification of each canceled speculative prefetch to a higher-level memory component that is local to the respective first or second processor.