Abstract: A data fabric routes requests between the plurality of requestors and the plurality of responders. The data fabric includes a crossbar router, a coherent slave controller coupled to the crossbar router, and a probe filter coupled to the coherent slave controller and tracking the state of cached lines of memory. Power state control circuitry operates, responsive to detecting any of a plurality of designated conditions, to cause the probe filter to enter a retention low power state in which a clock signal to the probe filter is gated while power is maintained to the probe filter. Entering the retention low power state is performed when all in-process probe filter lookups are complete.

Abstract: A coherent memory fabric includes a plurality of coherent master controllers and a coherent slave controller. The plurality of coherent master controllers each include a response data buffer. The coherent slave controller is coupled to the plurality of coherent master controllers. The coherent slave controller, responsive to determining a selected coherent block read command is guaranteed to have only one data response, sends a target request globally ordered message to the selected coherent master controller and transmits responsive data. The selected coherent master controller, responsive to receiving the target request globally ordered message, blocks any coherent probes to an address associated with the selected coherent block read command until receipt of the responsive data is acknowledged by a requesting client.

Abstract: Systems, apparatuses, and methods for maintaining a region-based cache directory are disclosed. A system includes multiple processing nodes, with each processing node including a cache subsystem. The system also includes a cache directory to help manage cache coherency among the different cache subsystems of the system. In order to reduce the number of entries in the cache directory, the cache directory tracks coherency on a region basis rather than on a cache line basis, wherein a region includes multiple cache lines. Accordingly, the system includes a region-based cache directory to track regions which have at least one cache line cached in any cache subsystem in the system. The cache directory includes a reference count in each entry to track the aggregate number of cache lines that are cached per region. If a reference count of a given entry goes to zero, the cache directory reclaims the given entry.

Abstract: Systems, apparatuses, and methods for implementing a speculative probe mechanism are disclosed. A system includes at least multiple processing nodes, a probe filter, and a coherent slave. The coherent slave includes an early probe cache to cache recent lookups to the probe filter. The early probe cache includes entries for regions of memory, wherein a region includes a plurality of cache lines. The coherent slave performs parallel lookups to the probe filter and the early probe cache responsive to receiving a memory request. An early probe is sent to a first processing node responsive to determining that a lookup to the early probe cache hits on a first entry identifying the first processing node as an owner of a first region targeted by the memory request and responsive to determining that a confidence indicator of the first entry is greater than a threshold.

Abstract: A data fabric routes requests between the plurality of requestors. A probe filter tracks the state of cached lines of memory at a probe filter coupled to the data fabric. Responsive to the data fabric leaving a non-operational power state while all requestors that are probe filter clients are in a non-operational power state, the power management controller delays a probe filter initialization state in which data regarding cached lines is initialized following the non-operational power state.

Abstract: A coherent memory fabric includes a plurality of coherent master controllers and a coherent slave controller. The plurality of coherent master controllers each include a response data buffer. The coherent slave controller is coupled to the plurality of coherent master controllers. The coherent slave controller, responsive to determining a selected coherent block read command is guaranteed to have only one data response, sends a target request globally ordered message to the selected coherent master controller and transmits responsive data. The selected coherent master controller, responsive to receiving the target request globally ordered message, blocks any coherent probes to an address associated with the selected coherent block read command until receipt of the responsive data is acknowledged by a requesting client.

Abstract: A data processing system includes a plurality of coherent masters, a plurality of coherent slaves, and a coherent data fabric. The coherent data fabric has upstream ports coupled to the plurality of coherent masters and downstream ports coupled to the plurality of coherent slaves for selectively routing accesses therebetween. The coherent data fabric includes a probe filter and a directory cleaner. The probe filter is associated with at least one of the downstream ports and has a plurality of entries that store information about each entry. The directory cleaner periodically scans the probe filter and selectively removes a first entry from the probe filter after the first entry is scanned.

Abstract: A data fabric routes requests between the plurality of requestors and the plurality of responders. The data fabric includes a crossbar router, a coherent slave controller coupled to the crossbar router, and a probe filter coupled to the coherent slave controller and tracking the state of cached lines of memory. Power state control circuitry operates, responsive to detecting any of a plurality of designated conditions, to cause the probe filter to enter a retention low power state in which a clock signal to the probe filter is gated while power is maintained to the probe filter. Entering the retention low power state is performed when all in-process probe filter lookups are complete.

Abstract: A data fabric routes requests between the plurality of requestors. A probe filter tracks the state of cached lines of memory at a probe filter coupled to the data fabric. Responsive to the data fabric leaving a non-operational power state while all requestors that are probe filter clients are in a non-operational power state, the power management controller delays a probe filter initialization state in which data regarding cached lines is initialized following the non-operational power state.

Abstract: A data fabric routes requests between the plurality of requestors and the plurality of responders. The data fabric includes a crossbar router, a coherent slave controller coupled to the crossbar router, and a probe filter coupled to the coherent slave controller and tracking the state of cached lines of memory. Power state control circuitry operates, responsive to detecting any of a plurality of designated conditions, to cause the probe filter to enter a retention low power state in which a clock signal to the probe filter is gated while power is maintained to the probe filter. Entering the retention low power state is performed when all in-process probe filter lookups are complete.

Abstract: Systems, apparatuses, and methods for maintaining region-based cache directories split between node and memory are disclosed. The system with multiple processing nodes includes cache directories split between the nodes and memory to help manage cache coherency among the nodes' cache subsystems. In order to reduce the number of entries in the cache directories, the cache directories track coherency on a region basis rather than on a cache line basis, wherein a region includes multiple cache lines. Each processing node includes a node-based cache directory to track regions which have at least one cache line cached in any cache subsystem in the node. The node-based cache directory includes a reference count field in each entry to track the aggregate number of cache lines that are cached per region. The memory-based cache directory includes entries for regions which have an entry stored in any node-based cache directory of the system.

Abstract: Systems, apparatuses, and methods for maintaining region-based cache directories split between node and memory are disclosed. The system with multiple processing nodes includes cache directories split between the nodes and memory to help manage cache coherency among the nodes' cache subsystems. In order to reduce the number of entries in the cache directories, the cache directories track coherency on a region basis rather than on a cache line basis, wherein a region includes multiple cache lines. Each processing node includes a node-based cache directory to track regions which have at least one cache line cached in any cache subsystem in the node. The node-based cache directory includes a reference count field in each entry to track the aggregate number of cache lines that are cached per region. The memory-based cache directory includes entries for regions which have an entry stored in any node-based cache directory of the system.

Abstract: Systems, apparatuses, and methods for maintaining a region-based cache directory are disclosed. A system includes multiple processing nodes, with each processing node including a cache subsystem. The system also includes a cache directory to help manage cache coherency among the different cache subsystems of the system. In order to reduce the number of entries in the cache directory, the cache directory tracks coherency on a region basis rather than on a cache line basis, wherein a region includes multiple cache lines. Accordingly, the system includes a region-based cache directory to track regions which have at least one cache line cached in any cache subsystem in the system. The cache directory includes a reference count in each entry to track the aggregate number of cache lines that are cached per region. If a reference count of a given entry goes to zero, the cache directory reclaims the given entry.

Abstract: Systems, apparatuses, and methods for maintaining a region-based cache directory are disclosed. A system includes multiple processing nodes, with each processing node including a cache subsystem. The system also includes a cache directory to help manage cache coherency among the different cache subsystems of the system. In order to reduce the number of entries in the cache directory, the cache directory tracks coherency on a region basis rather than on a cache line basis, wherein a region includes multiple cache lines. Accordingly, the system includes a region-based cache directory to track regions which have at least one cache line cached in any cache subsystem in the system. The cache directory includes a reference count in each entry to track the aggregate number of cache lines that are cached per region. If a reference count of a given entry goes to zero, the cache directory reclaims the given entry.

Abstract: A coherency management device receives requests to read data from or write data to an address in a main memory. On a write, if the data includes zero data, an entry corresponding to the memory address is created in a cache directory if it does not already exist, is set to an invalid state, and indicates that the data includes zero data. The zero data is not written to main memory or a cache. On a read, the cache directory is checked for an entry corresponding to the memory address. If the entry exists in the cache directory, is invalid, and includes an indication that data corresponding to the memory address includes zero data, the coherency management device returns zero data in response to the request without fetching the data from main memory or a cache.

Abstract: Systems, apparatuses, and methods for implementing a speculative probe mechanism are disclosed. A system includes at least multiple processing nodes, a probe filter, and a coherent slave. The coherent slave includes an early probe cache to cache recent lookups to the probe filter. The early probe cache includes entries for regions of memory, wherein a region includes a plurality of cache lines. The coherent slave performs parallel lookups to the probe filter and the early probe cache responsive to receiving a memory request. An early probe is sent to a first processing node responsive to determining that a lookup to the early probe cache hits on a first entry identifying the first processing node as an owner of a first region targeted by the memory request and responsive to determining that a confidence indicator of the first entry is greater than a threshold.

Abstract: Systems, apparatuses, and methods for accelerating accesses to private regions in a region-based cache directory scheme are disclosed. A system includes multiple processing nodes, one or more memory devices, and one or more region-based cache directories to manage cache coherence among the nodes' cache subsystems. Region-based cache directories track coherence on a region basis rather than on a cache line basis, wherein a region includes multiple cache lines. The cache directory entries for regions that are only accessed by a single node are cached locally at the node. Updates to the reference count for these entries are made locally rather than sending updates to the cache directory. When a second node accesses a first node's private region, the region is now considered shared, and the entry for this region is transferred from the first node back to the cache directory.

Abstract: Systems, apparatuses, and methods for maintaining region-based cache directories split between node and memory are disclosed. The system with multiple processing nodes includes cache directories split between the nodes and memory to help manage cache coherency among the nodes' cache subsystems. In order to reduce the number of entries in the cache directories, the cache directories track coherency on a region basis rather than on a cache line basis, wherein a region includes multiple cache lines. Each processing node includes a node-based cache directory to track regions which have at least one cache line cached in any cache subsystem in the node. The node-based cache directory includes a reference count field in each entry to track the aggregate number of cache lines that are cached per region. The memory-based cache directory includes entries for regions which have an entry stored in any node-based cache directory of the system.

Abstract: Systems, apparatuses, and methods for implementing a speculative probe mechanism are disclosed. A system includes at least multiple processing nodes, a probe filter, and a coherent slave. The coherent slave includes an early probe cache to cache recent lookups to the probe filter. The early probe cache includes entries for regions of memory, wherein a region includes a plurality of cache lines. The coherent slave performs parallel lookups to the probe filter and the early probe cache responsive to receiving a memory request. An early probe is sent to a first processing node responsive to determining that a lookup to the early probe cache hits on a first entry identifying the first processing node as an owner of a first region targeted by the memory request and responsive to determining that a confidence indicator of the first entry is greater than a threshold.

Abstract: Systems, apparatuses, and methods for maintaining region-based cache directories split between node and memory are disclosed. The system with multiple processing nodes includes cache directories split between the nodes and memory to help manage cache coherency among the nodes' cache subsystems. In order to reduce the number of entries in the cache directories, the cache directories track coherency on a region basis rather than on a cache line basis, wherein a region includes multiple cache lines. Each processing node includes a node-based cache directory to track regions which have at least one cache line cached in any cache subsystem in the node. The node-based cache directory includes a reference count field in each entry to track the aggregate number of cache lines that are cached per region. The memory-based cache directory includes entries for regions which have an entry stored in any node-based cache directory of the system.