摘要:
An LBIST captures pseudo-random values from a pseudo-random pattern generator. Next, the LBIST stabilizes an untimed logic path by inputting the captured pseudo-random value into the untimed logic path. In turn, the LBIST tests one or more timed signal transitions that are dependent upon the stabilized untimed logic path.
摘要:
An LBIST captures pseudo-random values from a pseudo-random pattern generator. Next, the LBIST stabilizes an untimed logic path by inputting the captured pseudo-random value into the untimed logic path. In turn, the LBIST tests one or more timed signal transitions that are dependent upon the stabilized untimed logic path.
摘要:
A multiprocessor data processing system includes at least first and second coherency domains, where the first coherency domain includes a system memory and a cache memory. According to a method of data processing, a cache line is buffered in a data array of the cache memory and a state field in a cache directory of the cache memory is set to a coherency state to indicate that the cache line is valid in the data array, that the cache line is held in the cache memory non-exclusively, and that another cache in said second coherency domain may hold a copy of the cache line.
摘要:
In response to a data request of a first of a plurality of processing units, the first processing unit selects a victim cache line to be castout from the lower level cache of the first processing unit and determines whether a mode is set. If not, the first processing unit issues on the interconnect fabric an LCO command identifying the victim cache line and indicating that a lower level cache is the intended destination. If the mode is set, the first processing unit issues a castout command with an alternative intended destination. In response to a coherence response to the LCO command indicating success of the LCO command, the first processing unit removes the victim cache line from its lower level cache, and the victim cache line is held elsewhere in the data processing system. The mode can be set to inhibit castouts to system memory, for example, for testing.
摘要:
A processing unit includes a processor core and a cache memory coupled to the processor core. The cache memory includes a data array, a directory of the data array, error detection logic that sequentially detects a first, second and third correctable errors in the data array of the cache memory and provides indications of detection of the first, second and third correctable errors, and control circuitry that, responsive to the indication of the third correctable error and an indication that the first and second correctable errors occurred at too high a frequency, marks an entry of the data array containing a cache line having the third correctable error as deleted in the directory of the cache memory regardless of which entry of the data array contains a cache line having the second correctable error.
摘要:
A processing unit for a multiprocessor data processing system includes a processor core and a cache hierarchy coupled to the processor core to provide low latency data access. The cache hierarchy includes an upper level cache coupled to the processor core and a lower level victim cache coupled to the upper level cache. In response to a prefetch request of the processor core that misses in the upper level cache, the lower level victim cache determines whether the prefetch request misses in the directory of the lower level victim cache and, if so, allocates a state machine in the lower level victim cache that services the prefetch request by issuing the prefetch request to at least one other processing unit of the multiprocessor data processing system.
摘要:
A processing unit includes a processor core and a cache memory coupled to the processor core. The cache memory includes a data array, a directory of the data array, error detection logic that sequentially detects a first, second and third correctable errors in the data array of the cache memory and provides indications of detection of the first, second and third correctable errors, and control circuitry that, responsive to the indication of the third correctable error and an indication that the first and second correctable errors occurred at too high a frequency, marks an entry of the data array containing a cache line having the third correctable error as deleted in the directory of the cache memory regardless of which entry of the data array contains a cache line having the second correctable error.
摘要:
In response to a data request, a victim cache line is selected for castout from a lower level cache, and a target lower level cache of one of the plurality of processing units is selected. A determination is made whether the selected target lower level cache has provided more than a threshold number of retry responses to lateral castout (LCO) commands of the first lower level cache, and if so, a different target lower level cache is selected. The first processing unit thereafter issues a LCO command on the interconnect fabric. The LCO command identifies the victim cache line to be castout and indicates that the target lower level cache is an intended destination of the victim cache line. In response to a successful coherence response to the LCO command, the victim cache line is removed from the first lower level cache and held in the second lower level cache.
摘要:
An opaque memory region for a bridge of an I/O adapter. The opaque memory region is inaccessible to memory transactions which traverse the bridge either from a primary bus to secondary bus or secondary bus to primary bus. As a result, memory transactions which target the opaque memory region are ignored by the bridge, allowing for the same address to exist on both sides of the bridge with different data stored in each. The implementation of the opaque memory region provides a means to complete memory transactions within I/O adapter subsystem memory, hence, relieving host computer system memory resources. In addition, a number of I/O adapters can be used in a host computer system where the host and all the I/O devices use some of the same memory addresses.
摘要:
In response to a memory access request of a processor core that targets a target cache line, the lower level cache of a vertical cache hierarchy associated with the processor core supplies a copy of the target cache line to an upper level cache in the vertical cache hierarchy and retains a copy in a shared coherence state. The upper level cache holds the copy of the target cache line in a private shared ownership coherence state indicating that each cached copy of the target memory block is cached within the vertical cache hierarchy associated with the processor core. In response to the upper level cache signaling replacement of the copy of the target cache line in the private shared ownership coherence state, the lower level cache updates its copy of the target cache line to the exclusive ownership coherence state without coherency messaging with other vertical cache hierarchies.