Abstract: A processor contains multiple levels of registers having different access latency. A relatively smaller set of registers is contained in a relatively faster higher level register bank, and a larger, more complete set of the registers is contained in a relatively slower lower level register bank. Physically, the higher level register bank is placed closer to functional logic which receives inputs from the registers. Selection logic enables selecting output of either register bank for input to processor execution logic. Preferably, the lower level bank includes a complete set of all processor registers, and the higher level bank includes a smaller subset of the registers, duplicating information in the lower level bank. The higher level bank is preferably accessible in a single clock cycle.

Abstract: A method and a cache control circuit for replacing a cache line using an alternate pseudo least-recently-used (PLRU) algorithm with a victim cache coherency state, and a design structure on which the subject cache control circuit resides are provided. When a requirement for replacement in a congruence class is identified, a first PLRU cache line for replacement and an alternate PLRU cache line for replacement in the congruence class are calculated. When the first PLRU cache line for replacement is in the victim cache coherency state, the alternate PLRU cache line is picked for use.

Abstract: A method and a cache control circuit for replacing a cache line using an alternate pseudo least-recently-used (PLRU) algorithm with a victim cache coherency state, and a design structure on which the subject cache control circuit resides are provided. When a requirement for replacement in a congruence class is identified, a first PLRU cache line for replacement and an alternate PLRU cache line for replacement in the congruence class are calculated. When the first PLRU cache line for replacement is in the victim cache coherency state, the alternate PLRU cache line is picked for use.

Abstract: A processor contains multiple levels of registers having different access latency. A relatively smaller set of registers is contained in a relatively faster higher level register bank, and a larger, more complete set of the registers is contained in a relatively slower lower level register bank. Physically, the higher level register bank is placed closer to functional logic which receives inputs from the registers. Preferably, the lower level bank includes a complete set of all processor registers, and the higher level bank includes a smaller subset of the registers, duplicating information in the lower level bank. The higher level bank is preferably accessible in a single clock cycle.

Abstract: In a first aspect, a stream of data is transmitted by dividing the stream of data into a first substream and a second substream, transmitting the first substream in a first data channel, and transmitting the second substream in a second data channel. Before transmitting the first and second substreams, a first marker signal is inserted in the first substream and/or a second marker signal is inserted in the second substream. A receiver circuit receives the substreams, detects at least one marker signal, and reassembles the data stream from the substreams based on at least one detected marker signal. Numerous other aspects are provided.

Abstract: In a first aspect, a stream of data is transmitted by dividing the stream of data into a first substream and a second substream, transmitting the first substream in a first data channel, and transmitting the second substream in a second data channel. Before transmitting the first and second substreams, a first marker signal is inserted in the first substream and/or a second marker signal is inserted in the second substream. A receiver circuit receives the substreams, detects at least one marker signal, and reassembles the data stream from the substreams based on at least one detected marker signal. Numerous other aspects are provided.

Abstract: A method of deskewing parallel data streams includes receiving the plurality of data streams and storing each of the received data streams in a respective buffer. Synchronization signals in the data streams are detected, and the buffers are controlled to read out the stored data streams on the basis of the detected synchronization signals. Numerous other methods and apparatus are provided.

Abstract: A multithreaded processor and a method for performance monitoring within a multithreaded processor are described. According to the present invention, execution circuitry within the multithreaded processor executes instructions in an active thread among first and second concurrent threads, while buffering circuitry buffers instructions and/or data of an inactive one of the first and second concurrent threads. Thread switch logic in the multithreaded processor switches threads by activating the inactive thread and inactivating the active thread. The operation of the multithreaded processor is monitored by a performance monitor, which records occurrences of an event generated by switching threads.

Abstract: Performance monitoring capabilities are expanded to an entire data processing system so that performance analyses can be made for operations occurring within the entire data processing system and not merely within the processor or any other device containing the performance monitor. Therefore, there is a provision for communicating performance monitor-related signals between the various performance monitors within the various devices and processor within a data processing system.

Abstract: A method and system for instruction trace reconstruction utilizing performance monitor outputs and bus monitoring. Performance projections for processor systems and memory subsystems are important for a correct understanding of work loads within the system. An instruction trace is generally utilized to determine distribution of instructions, identification of register dependencies, branch path analyzes and timing. One well known technique for reconstructing an instruction trace can be accomplished by monitoring bus traffic to determine instruction addresses, data addresses and data during the trace, if the initial architectural state of the system is known. The difficulty in reconstructing an instruction trace from monitored bus traffic can be decreased substantially if more definitive information regarding the actual instruction sequence can be obtained.

Abstract: A method and system for performance monitoring within a multithreaded processor are provided. The system includes a processor responsive to instructions within first and second threads and a performance monitor that separately records a first event generated by the processor in response to the first thread and a second event generated by the processor in response to the second thread. In one embodiment, the processor has first and second modes of operation. In this embodiment, when the performance monitor is operating in the first mode, a first counter within the performance monitor increments in response to each occurrence of the first event and a second counter within the performance monitor increments in response to each occurrence of the second event. Alternatively, when the performance monitor is operating in the second mode, the first counter increments in response to each occurrence of the first event and in response to each occurrence of the second event.