摘要:
A method and apparatus are disclosed for releasing functional units in a multithreaded very large instruction word (VLIW) processor. The functional unit release mechanism can retrieve the capacity lost due to multiple cycle instructions. The functional unit release mechanism of the present invention permits idle functional units to be reallocated to other threads, thereby improving workload efficiency. Instruction packets are assigned to functional units, which can maintain their state, independent of the issue logic. Each functional unit has an associated state machine (SM) that keeps track of the number of cycles that the functional unit will be occupied by a multiple-cycle instruction. Functional units do not reassign themselves as long as the functional unit is busy. When the instruction is complete, the functional unit can participate in functional unit allocation, even if other functional units assigned to the same thread are still busy. The functional unit release approach of the present invention allows the functional units that are not associated with a multiple-cycle instruction to be allocated to other threads while the blocked thread is waiting, thereby improving throughput of the multithreaded VLIW processor. Since the state is associated with each functional unit separately from the instruction issue unit, the functional units can be assigned to threads independently of the state of any one thread and its constituent instructions.
摘要:
A method and apparatus are disclosed for allocating functional units in a multithreaded very large instruction word (VLIW) processor. The present invention combines the techniques of conventional VLIW architectures and conventional multithreaded architectures to reduce execution time within an individual program, as well as across a workload. The present invention utilizes a compiler to detect parallelism. The disclosed multithreaded VLIW architecture exploits program parallelism by issuing multiple instructions, in a similar manner to single threaded VLIW processors, from a single program sequencer, and also supports multiple program sequencers, as in simultaneous multithreading. Instructions are allocated to functional units to issue multiple VLIW instructions to multiple functional units in the same cycle. The allocation mechanism of the present invention occupies a pipeline stage just before arguments are dispatched to functional units. The allocate stage determines how to group the instructions together to maximize efficiency, by selecting appropriate instructions and assigning the instructions to the FUs. The criteria for selection are thread priority or resource availability or both. Under the thread priority criteria, different threads can have different priorities. The allocate stage selects and forwards the packets (or instructions from packets) for execution belonging to the thread with the highest priority according to the priority policy implemented. Under the resource availability criteria, a packet (having up to K instructions) can be allocated only if the resources (functional units) required by the packet are available for the next cycle. Functional units report their availability to the allocate stage.
摘要:
A method and apparatus are disclosed for allocating functional units in a multithreaded very large instruction word (VLIW) processor. The present invention combines the techniques of conventional very long instruction word architectures and conventional multithreaded architectures to reduce execution time within an individual program, as well as across a workload. The present invention utilizes instruction packet splitting to recover some efficiency lost with conventional multithreaded architectures. Instruction packet splitting allows an instruction bundle to be partially issued in one cycle, with the remainder of the bundle issued during a subsequent cycle. The allocation hardware assigns as many instructions from each packet as will fit on the available functional units, rather than allocating all instructions in an instruction packet at one time. Those instructions that cannot be allocated to a functional unit are retained in a ready-to-run register. On subsequent cycles, instruction packets in which all instructions have been issued to functional units are updated from their thread's instruction stream, while instruction packets with instructions that have been held are retained. The functional unit allocation logic can then assign instructions from the newly-loaded instruction packets as well as instructions that were not issued from the retained instruction packets.
摘要:
A method and apparatus are disclosed for allocating functional units in a multithreaded very large instruction word (VLIW) processor. The present invention combines the techniques of conventional very long instruction word (VLIW) architectures and conventional multithreaded architectures to reduce execution time within an individual program, as well as across a workload. The present invention utilizes instruction packet splitting to recover some efficiency lost with conventional multithreaded architectures. Instruction packet splitting allows an instruction bundle to be partially issued in one cycle, with the remainder of the bundle issued during a subsequent cycle. There are times, however, when instruction packets cannot be split without violating the semantics of the instruction packet assembled by the compiler. A packet split identification bit is disclosed that allows hardware to efficiently determine when it is permissible to split an instruction packet. The split bit informs the hardware when splitting is prohibited. The allocation hardware assigns as many instructions from each packet as will fit on the available functional units, rather than allocating all instructions in an instruction packet at one time, provided the split bit has not been set. Those instructions that cannot be allocated to a functional units are retained in a ready-to-run register. On subsequent cycles, instruction packets in which all instructions have been issued to functional units are updated from their thread's instruction stream, while instruction packets with instructions that have been held are retained. The functional unit allocation logic can then assign instructions from the newly-loaded instruction packets as well as instructions that were not issued from the retained instruction packets.
摘要:
A method includes storing first and second sets of parameters in a register. Each set of parameters defines a storage transaction to store data to a computer readable medium or a retrieval transaction to retrieve data from the computer readable medium. The first storage or retrieval transaction is performed according to the first set of parameters. The second set of parameters is retrieved from the register automatically when the first storage or retrieval transaction is completed, without waiting for a further command from a control processor. The second storage or retrieval transaction is performed according to the retrieved second set of parameters. A system for performing the method and a computer readable medium containing pseudocode for generating an application specific integrated circuit that performs the method are provided.
摘要:
Disclosed is a vector indexed memory unit and method of operation. In one embodiment a plurality of values are stored in segments of a vector index register. Individual ones of the values are provided to an associated operator (e.g., adder or bit replacement). Individual ones of the operators operates on its associated vector index value and a base value to generate a memory address. These memory addresses are then concurrently accessed in one or more memory units. If the data in the memory units are organized as data tables, the apparatus allows for multiple concurrent table lookups. In an alternate embodiment, in addition to the above described operators generating multiple memory addresses, an adder is provided to add the base value to the value represented by the concatenation of the bits in the vector index register to generate a single memory address. Multiplexers controlled by a programmable mode select signal are used to provide either the multiple memory addresses or the single memory address to the memory units. This alternate embodiment provides an apparatus that can programmably function in either an vector indexed memory mode or a conventional memory addressing mode.
摘要:
Disclosed is a vector indexed memory unit and method of operation. In one embodiment a plurality of values are stored in segments of a vector index register. Individual ones of the values are provided to an associated operator (e.g., adder or bit replacement). Individual ones of the operators operates on its associated vector index value and a base value to generate a memory address. These memory addresses are then concurrently accessed in one or more memory units. If the data in the memory units are organized as data tables, the apparatus allows for multiple concurrent table lookups. In an alternate embodiment, in addition to the above described operators generating multiple memory addresses, an adder is provided to add the base value to the value represented by the concatenation of the bits in the vector index register to generate a single memory address. Multiplexers controlled by a programmable mode select signal are used to provide either the multiple memory addresses or the single memory address to the memory units. This alternate embodiment provides an apparatus that can programmably function in either an vector indexed memory mode or a conventional memory addressing mode.
摘要:
In a system having a control processor, an apparatus is provided with at least one memory. The at least one memory includes a first memory portion for storing at least one first decryption key. A decryption engine uses the first decryption key to decrypt information. A key processor provides the first decryption key to the decryption engine without allowing the control processor to access the first decryption key. A system incorporating the key processing apparatus and a method of using the apparatus are also provided.
摘要:
Disclosed is a vector indexed memory unit and method of operation. In one embodiment a plurality of values are stored in segments of a vector index register. Individual ones of the values are provided to an associated operator (e.g., adder or bit replacement). Individual ones of the operators operates on its associated vector index value and a base value to generate a memory address. These memory addresses are then concurrently accessed in one or more memory units. If the data in the memory units are organized as data tables, the apparatus allows for multiple concurrent table lookups. In an alternate embodiment, in addition to the above described operators generating multiple memory addresses, an adder is provided to add the base value to the value represented by the concatenation of the bits in the vector index register to generate a single memory address. Multiplexers controlled by a programmable mode select signal are used to provide either the multiple memory addresses or the single memory address to the memory units. This alternate embodiment provides an apparatus that can programmably function in either an vector indexed memory mode or a conventional memory addressing mode.
摘要:
An apparatus and method are provided for extracting connection information from a traffic header in a communications network. The apparatus includes a first storage element containing a first look-up table for determining a first data packet header offset and data size for extracting a communications protocol type from the header and a second storage element containing a second look-up table for determining from the communications protocol type a second data packet header offset and second data size for extracting a connection address from the header. The storage elements may be in the form of content-addressable memories. Exception handling and hardware initialization can be controlled by a system processor.