摘要:
A dual system shared cache directory structure for a cache memory performs the role of an inclusive shared system cache, i.e., data, and system control, i.e., coherency. The system includes two separate system cache directories in the shared system cache. The two separate cache directories are substantially equal in size and collectively large enough to contain all of the processor cache directory entries, but with only one of these separate cache directories hosting system-cache data to back the most recent fraction of data accessed by the processors. The other cache directory retains only addresses, including addresses of lines LRUed out from the first cache directory and the identity of the processor using the data. Thus by this expedient, only the directory known to be backed by system cached data will be evaluated for system cache memory data.
摘要:
Portions of data in a processor system are stored in a slower main memory and are transferred to a faster memory comprising a hierarchy of cache structures between one or more processors and the main memory. For a system with shared L2 cache(s) between the processor(s) and the main memory, an individual L1 cache of a processor must first communicate to an associated L2 cache(s), or check with such L2 cache(s), to obtain a copy of a particular line from a given cache location prior to, or upon modification, or appropriation of data at a given cached location. The individual L1 cache further includes provisions for notifying the L2 cache(s) upon determining when the data stored in the particular cache line in the L1 cache has been replaced, and when the particular cache line is disowned by an L1 cache, the L2 cache is updated to change the state of the particular cache line therein from an ownership state of exclusive to a particular identified CPU to an ownership state of exclusive to no CPU, thereby allowing reduction of cross interrogate delays during another processor acquisition of the same cache line.
摘要:
Caching where portions of data are stored in slower main memory and are transferred to faster memory between one or more processors and the main memory. The cache is such that an individual cache system must communicate to other associated cache systems, or check with such cache systems, to determine if they contain a copy of a given cached location prior to or upon modification or appropriation of data at a given cached location. The cache further includes provisions for determining when the data stored in a particular memory location may be replaced.
摘要:
Caching where portions of data are stored in slower main memory and are transferred to faster memory between one or more processors and the main memory. The cache is such that an individual cache system must communicate to other associated cache systems, or check with such cache systems, to determine if they contain a copy of a given cached location prior to or upon modification or appropriation of data at a given cached location. The cache further includes provisions for determining when the data stored in a particular memory location may be replaced.
摘要:
A method and apparatus for implementing a combined data/coherency cache for a shared memory multi-processor. The combined data/coherency cache includes a system cache with a number of entries. The method includes building a system cache directory with a number of entries equal to the number of entries of the system cache. The building includes designating a number of sub-entries for each entry which is determined by a number of sub-entries operable for performing system cache coherency functions. The building also includes providing a sub-entry logic designator for each entry, and mapping one of the sub-entries for each entry to the system cache via the sub-entry logic designator.
摘要:
The system and method described herein is a dual system directory structure that performs the role of system cache, i.e., data, and system control, i.e., coherency. The system includes two system cache directories. These two cache directories are equal in size and collectively large enough to contain all of the processor cache directory entries, but with only one of these cache directories hosting system-cache data to back the most recent fraction of data accessed by the processors, and the other cache directory retains only addreses, including addresses of lines LRUed out and the processor using the data. By this expedient, only the directory known to be backed by system cached data will be evaluated for system cache data hits.
摘要:
A method and apparatus for implementing a combined data/coherency cache for a shared memory multi-processor. The combined data/coherency cache includes a system cache with a number of entries. The method includes building a system cache directory with a number of entries equal to the number of entries of the system cache. The building includes designating a number of sub-entries for each entry which is determined by a number of sub-entries operable for performing system cache coherency functions. The building also includes providing a sub-entry logic designator for each entry, and mapping one of the sub-entries for each entry to the system cache via the sub-entry logic designator.
摘要:
A two pipe pass method for least recently used (LRU) compartment capture in a multiprocessor system. The method includes receiving a fetch request via a requesting processor and accessing a cache directory based on the received fetch request, performing a first pipe pass by determining whether a fetch hit or a fetch miss has occurred in the cache directory, and determining an LRU compartment associated with a specified congruence class of the cache directory based on the fetch request received, when it is determined that a fetch miss has occurred, and performing a second pipe pass by using the LRU compartment determined and the specified congruence class to access the cache directory and to select an LRU address to be cast out of the cache directory.
摘要:
A method and apparatus are disclosed for performing maintenance operations in a system using address, data, and controls which are transported through the system, allowing for parallel and serial operations to co-exist without the parallel operations being slowed down by the serial ones. It also provides for use of common shifters, engines, and protocols as well as efficient conversion of ECC to parity and parity to ECC as needed in the system. The invention also provides for error detection and isolation, both locally and in the reported status. The invention provides for large maintenance address and data spaces (typically 64 bits address and 64 bits data per address supported).
摘要:
Systems, methods and computer program products for data buffers partitioned from a cache array. An exemplary embodiment includes a method in a processor and for providing data buffers partitioned from a cache array, the method including clearing cache directories associated with the processor to an initial state, obtaining a selected directory state from a control register preloaded by the service processor, in response to the control register including the desired cache state, sending load commands with an address and data, loading cache lines and cache line directory entries into the cache and storing the specified data in the corresponding cache line.