The present disclosure provides a method and a system of verifying access by a multi-core interconnect to an L2 cache in order to solve problems of delays and difficulties in locating errors and generating check expectation results. A consistency transmission monitoring circuitry detects, in real time, interactions among a multi-core interconnects system, all single-core processors, an L2 cache and a primary memory, and sends collected transmission information to an L2 cache expectation generator and a check circuitry. The L2 cache expectation generator obtains information from a global memory precise control circuitry according to a multi-core consistency protocol and generates an expected result. The check circuitry is responsible for comparing the expected result with an actual result, thus implementing determination of multi-core interconnect's access accuracy to the L2 cache without delay.

Methods, apparatus, systems, and articles of manufacture are disclosed that reduce latency and bandwidth consumption when sharing memory across a distributed coherent Edge computing system. The distributed coherent Edge computing system disclosed herein configures a compute express link (CXL) endpoint to share data between memories across an Edge platform. The CXL endpoint configures coherent memory domain(s) of memory addresses, which are initialized from an Edge device connected to the Edge platform. The CXL endpoint also configures coherency rule(s) for the coherent memory domain(s). The CXL endpoint is implemented to snoop the Edge platform in response to read and write requests from the Edge device. The CXL endpoint selectively snoops memory addresses within the coherent memory domain(s) that are defined as coherent based on the coherency rule(s).

Techniques for loading data, comprising receiving a memory management command to perform a memory management operation to load data into the cache memory before execution of an instruction that requests the data, formatting the memory management command into one or more instruction for a cache controller associated with the cache memory, and outputting an instruction to the cache controller to load the data into the cache memory based on the memory management command.

A device includes a data path, a first interface configured to receive a first memory access request from a first peripheral device, and a second interface configured to receive a second memory access request from a second peripheral device. The device further includes an arbiter circuit configured to, in a first clock cycle, a pre-arbitration winner between a first memory access request and a second memory access request based on a first number of credits allocated to a first destination device and a second number of credits allocated to a second destination device. The arbiter circuit is further configured to, in a second clock cycle select a final arbitration winner from among the pre-arbitration winner and a subsequent memory access request based on a comparison of a priority of the pre-arbitration winner and a priority of the subsequent memory access request.

In described examples, a coherent memory system includes a central processing unit (CPU), and first and second level caches, each with a cache controller. The CPU is arranged to execute program instructions to manipulate data in at least a first or second secure context. Each of the first and second caches stores a secure code for indicating the secure context by which data for a respective cache line is received. The first and second level caches maintain coherency in response to comparing the secure codes of respective lines of cache and executing a cache coherency operation in response. A requestor coupled to the second level cache may send a coherence read transaction to the second level cache controller, which upon an affirmative security check, generates a snoop read transaction and sends the same to the first level cache.

An apparatus includes a CPU core and a L1 cache subsystem including a L1 main cache, a L1 victim cache, and a L1 controller. The apparatus includes a L2 cache subsystem including a L2 main cache, a shadow L1 main cache, a shadow L1 victim cache, and a L2 controller configured to receive a read request from the L1 controller as a single transaction. Read request includes a read address, a first indication of an address and a coherence state of a cache line A to be moved from the L1 main cache to the L1 victim cache to allocate space for data returned in response to the read request, and a second indication of an address and a coherence state of a cache line B to be removed from the L1 victim cache in response to the cache line A being moved to the L1 victim cache.

A cache coherent interconnect connected to one or more agents, using Network Interface Units (NIUs), and also having one or more internal modules, such as a directory, is provided with one or more message builders and message receivers. These message builders and message receivers are provided as additional hardware IP blocks incorporated into the various NIUs and modules. When an agent signals an intention to enter/exit the cache coherent interconnect, a message communicating this information is generated using message builders, and transmitted using the interconnect wiring as a “virtual wire” to one or more message receivers associated with directories that need to be aware of the entry/exit transition of the agent. The directories are provided with tracking engines to manage the entry/exit information and status of the agent. Interconnects may include a broadcast engine to provide distribution to, and aggregate acknowledgements from, a single source to multiple destinations.

In a network-on-chip (NoC) interconnect connected to one or more agents with multiple input ports, one or more switches are provided with a round robin arbiter constructed to use representations of the input ports and, in some embodiments, the current round robin state, as thermometer codes. By using thermometer code to represent port information, the correspondence to the current input and the current state to be granted can be rapidly determined through a simple two-step AND and XOR operations. With such a simple logical procedure, the number of steps to make the determination, and therefore the energy required, can be reduced by log 2(n) steps or up to 43%. Using thermometer code reduces the number of computations required. Hence, the number of logic circuit elements required to carry out the calculation is reduced, shrinking the floorplan area needed for the arbiter.

Systems, apparatuses, and methods for reducing probe filter accesses in response to processing-in-memory (PIM) requests are disclosed. A coherent secondary unit receives PIM requests targeting a corresponding PIM device. For each PIM request that is received, the coherent secondary unit performs a lookup of a PIM address table (PAT). If the address of the PIM request matches an address of an existing entry in the PAT, the coherent secondary unit prevents the PIM request from being sent to a probe filter. Otherwise, if there is no match for the address of the PIM request in the entries of the PAT, the coherent secondary unit sends the PIM request to the probe filter, and the coherent secondary unit creates a new PAT entry for the address of the PIM request. Any subsequent PIM requests to the same address will match with the new entry in the PAT.

A system includes a non-coherent component; a coherent, non-caching component; a coherent, caching component; and a level two (L2) cache subsystem coupled to the non-coherent component, the coherent, non-caching component, and the coherent, caching component. The L2 cache subsystem includes a L2 cache; a shadow level one (L1) main cache; a shadow L1 victim cache; and a L2 controller. The L2 controller is configured to receive and process a first transaction from the non-coherent component; receive and process a second transaction from the coherent, non-caching component; and receive and process a third transaction from the coherent, caching component.