Abstract: A signal is transmitted from a sending chip to a first receiving chip in a communications ring via a first i/o set of the sending chip. A signal from the sending chip to a second receiving chip in the communications ring is transmitted via a second i/o set of the sending chip. The first i/o set corresponds to a first direction for the sending chip transmitting around the ring, and the second i/o set corresponds to a second direction for the sending chip transmitting around the ring. The transmitting via the first i/o set is for a circumstance where a number of chips interposed in the ring between the sending and receiving chips in the first direction is not greater than the number of chips interposed in the second direction. The transmitting via the second i/o set is for a circumstance where the number is greater.

Abstract: A processor includes at least one execution unit, an instruction sequencing unit coupled to the execution unit, and a plurality of caches at a same level. The caches, which store data utilized by the execution unit, have diverse cache hardware and each preferably store only data having associated addresses within a respective one of a plurality of subsets of an address space. The diverse cache hardware can include, for example, differing cache sizes, differing associativities, differing sectoring, and differing inclusivities.

Abstract: A method of improving memory access for a computer system, by sending load requests to a lower level storage subsystem along with associated information pertaining to intended use of the requested information by the requesting processor, without using a high level load queue. Returning the requested information to the processor along with the associated use information allows the information to be placed immediately without using reload buffers. A register load bus separate from the cache load bus (and having a smaller granularity) is used to return the information. An upper level (L1) cache may then be imprecisely reloaded (the upper level cache can also be imprecisely reloaded with store instructions). The lower level (L2) cache can monitor L1 and L2 cache activity, which can be used to select a victim cache block in the L1 cache (based on the additional L2 information), or to select a victim cache block in the L2 cache (based on the additional L1 information).

Abstract: A processor includes at least one execution unit, an instruction sequencing unit coupled to the execution unit, and a plurality of caches at a same level. The caches, which store data utilized by the execution unit, each store only data having associated addresses within a respective one of a plurality of subsets of an address space and implement diverse caching behaviors. The diverse caching behaviors can include differing memory update policies, differing coherence protocols, differing prefetch behaviors, and differing cache line replacement policies.

Abstract: A method of operating a multi-level memory hierarchy of a computer system and apparatus embodying the method, wherein instructions issue having an explicit prefetch request directly from an instruction sequence unit to a prefetch unit of the processing unit. The invention applies to values that are either operand data or instructions. In a preferred embodiment, two prefetch units are used, the first prefetch unit being hardware independent and dynamically monitoring one or more active streams associated with operations carried out by a core of the processing unit, and the second prefetch unit being aware of the lower level storage subsystem and sending with the prefetch request an indication that a prefetch value is to be loaded into a lower level cache of the processing unit.

Abstract: A method and apparatus for efficiently managing caches with non-power-of-two congruence classes allows for increasing the number of congruence classes in a cache when not enough area is available to double the cache size. One or more congruence classes within the cache have their associative sets split so that a number of congruence classes are created with reduced associativity. The management method and apparatus allow access to the congruence classes without introducing any additional cycles of delay or complex logic.

Abstract: A method of improving memory access for a computer system, by sending load requests to a lower level storage subsystem along with associated information pertaining to intended use of the requested information by the requesting processor, without using a high level load queue. Returning the requested information to the processor along with the associated use information allows the information to be placed immediately without using reload buffers. A register load bus separate from the cache load bus (and having a smaller granularity) is used to return the information. An upper level (L1) cache may then be imprecisely reloaded (the upper level cache can also be imprecisely reloaded with store instructions). The lower level (L2) cache can monitor L1 and L2 cache activity, which can be used to select a victim cache block in the L1 cache (based on the additional L2 information), or to select a victim cache block in the L2 cache (based on the additional L1 information).

Abstract: A method of operating a processing unit of a computer system, by issuing an instruction having an explicit prefetch request directly from an instruction sequence unit to a prefetch unit of the processing unit. The invention applies to values that are either operand data or instructions. In a preferred embodiment, two prefetch units are used, the first prefetch unit being hardware independent and dynamically monitoring one or more active streams associated with operations carried out by a core of the processing unit, and the second prefetch unit being aware of the lower level storage subsystem and sending with the prefetch request an indication that a prefetch value is to be loaded into a lower level cache of the processing unit. The invention may advantageously associate each prefetch request with a stream ID of an associated processor stream, or a processor ID of the requesting processing unit (the latter feature is particularly useful for caches which are shared by a processing unit cluster).

Abstract: A method of operating a processing unit of a computer system, by issuing an instruction having an explicit prefetch request directly from an instruction sequence unit to a prefetch unit of the processing unit. The invention applies to values that are either operand data or instructions. In a preferred embodiment, two prefetch units are used, the first prefetch unit being hardware independent and dynamically monitoring one or more active streams associated with operations carried out by a core of the processing unit, and the second prefetch unit being aware of the lower level storage subsystem and sending with the prefetch request an indication that a prefetch value is to be loaded into a lower level cache of the processing unit. The invention may advantageously associate each prefetch request with a stream ID of an associated processor stream, or a processor ID of the requesting processing unit (the latter feature is particularly useful for caches which are shared by a processing unit cluster).

Abstract: A method of operating a multi-level memory hierarchy of a computer system and apparatus embodying the method, wherein instructions issue having an explicit prefetch request directly from an instruction sequence unit to a prefetch unit of the processing unit. The invention applies to values that are either operand data or instructions and treats instructions in a different manner when they are loaded speculatively. These prefetch requests can be demand load requests, where the processing unit will need the operand data or instructions, or speculative load requests, where the processing unit may or may not need the operand data or instructions, but a branch prediction or stream association predicts that they might be needed. The load requests are sent to the lower level cache when the upper level cache does not contain the value required by the load.

Abstract: A method of improving memory access for a computer system, by sending load requests to a lower level storage subsystem along with associated information pertaining to intended use of the requested information by the requesting processor, without using a high level load queue. Returning the requested information to the processor along with the associated use information allows the information to be placed immediately without using reload buffers. A register load bus separate from the cache load bus (and having a smaller granularity) is used to return the information. An upper level (L1) cache may then be imprecisely reloaded (the upper level cache can also be imprecisely reloaded with store instructions). The lower level (L2) cache can monitor L1 and L2 cache activity, which can be used to select a victim cache block in the L1 cache (based on the additional L2 information), or to select a victim cache block in the L2 cache (based on the additional L1 information).

Abstract: A data processing system having a modified processor chip and external components to the processor chip. The processor chip is interconnected to the external components via point-to-point bus connections controlled by an integrated distributed switch (IDS) controller. The IDS controller is placed, during chip design, in the upper layer metals of the processor chip. When the data processing system is a multi-chip multiprocessor data processing system, the IDS controller operates to provide a pseudo switching effect whereby the processor is directly connected to each external component. The IDS controller permits the processor to have greater communication bandwidth and reduced latencies with the external components. It also allows for a connection to distributed external components such as memory and I/O, etc. with overall reduced system components.

Abstract: A method of improving memory access for a computer system, by sending load requests to a lower level storage subsystem along with associated information pertaining to intended use of the requested information by the requesting processor, without using a high level load queue. Returning the requested information to the processor along with the associated use information allows the information to be placed immediately without using reload buffers. A register load bus separate from the cache load bus (and having a smaller granularity) is used to return the information. An upper level (L1) cache may then be imprecisely reloaded (the upper level cache can also be imprecisely reloaded with store instructions). The lower level (L2) cache can monitor L1 and L2 cache activity, which can be used to select a victim cache block in the L1 cache (based on the additional L2 information), or to select a victim cache block in the L2 cache (based on the additional L1 information).

Abstract: A method of maintaining cache coherency, by designating one cache that owns a line as a highest point of coherency (HPC) for a particular memory block, and sending a snoop response from the cache indicating that it is currently the HPC for the memory block and can service a request. The designation may be performed in response to a particular coherency state assigned to the cache line, or based on the setting of a coherency token bit for the cache line. The processing units may be grouped into clusters, while the memory is distributed using memory arrays associated with respective clusters. One memory array is designated as the lowest point of coherency (LPC) for the memory block (i.e., a fixed assignment) while the cache designated as the HPC is dynamic (i.e., changes as different caches gain ownership of the line).

Abstract: A method of improving memory access for a computer system, by sending load requests to a lower level storage subsystem along with associated information pertaining to intended use of the requested information by the requesting processor, without using a high level load queue. Returning the requested information to the processor along with the associated use information allows the information to be placed immediately without using reload buffers. A register load bus separate from the cache load bus (and having a smaller granularity) is used to return the information. An upper level (L1) cache may then be imprecisely reloaded (the upper level cache can also be imprecisely reloaded with store instructions). The lower level (L2) cache can monitor L1 and L2 cache activity, which can be used to select a victim cache block in the L1 cache (based on the additional L2 information), or to select a victim cache block in the L2 cache (based on the additional L1 information).

Abstract: A method of operating a computer system is disclosed in which an instruction having an explicit prefetch request is issued directly from an instruction sequence unit to a prefetch unit of a processing unit. In a preferred embodiment, two prefetch units are used, the first prefetch unit being hardware independent and dynamically monitoring one or more active streams associated with operations carried out by a core of the processing unit, and the second prefetch unit being aware of the lower level storage subsystem and sending with the prefetch request an indication that a prefetch value is to be loaded into a lower level cache of the processing unit. The invention may advantageously associate each prefetch request with a stream ID of an associated processor stream, or a processor ID of the requesting processing unit (the latter feature is particularly useful for caches which are shared by a processing unit cluster).

Abstract: A method of improving memory access for a computer system, by sending load requests to a lower level storage subsystem along with associated information pertaining to intended use of the requested information by the requesting processor, without using a high level load queue. Returning the requested information to the processor along with the associated use information allows the information to be placed immediately without using reload buffers. A register load bus separate from the cache load bus (and having a smaller granularity) is used to return the information. An upper level (L1) cache may then be imprecisely reloaded (the upper level cache can also be imprecisely reloaded with store instructions). The lower level (L2) cache can monitor L1 and L2 cache activity, which can be used to select a victim cache block in the L1 cache (based on the additional L2 information), or to select a victim cache block in the L2 cache (based on the additional L1 information).

Abstract: A method of operating a computer system is disclosed in which an instruction having an explicit prefetch request is issued directly from an instruction sequence unit to a prefetch unit of a processing unit. In a preferred embodiment, two prefetch units are used, the first prefetch unit being hardware independent and dynamically monitoring one or more active streams associated with operations carried out by a core of the processing unit, and the second prefetch unit being aware of the lower level storage subsystem and sending with the prefetch request an indication that a prefetch value is to be loaded into a lower level cache of the processing unit. The invention may advantageously associate each prefetch request with a stream ID of an associated processor stream, or a processor ID of the requesting processing unit (the latter feature is particularly useful for caches which are shared by a processing unit cluster).

Abstract: An improved system for passenger safety in a front-end vehicle collision, whereby the kinetic energy of a passenger may be reduced before the passenger is exposed to the crash deceleration. An array of variably momentum-responsive electrical sensors mounted in the forward portion of the vehicle senses the onset of a front-end collision and sends one or more crash signals to the passenger compartment. A passenger seat is mounted on translating means permitting rearward motion and has a harness to secure a passenger to the seat. Beneath the seat, attached between the floor of the vehicle and the frame of the seat, is an array of pairs of linear actuators, each actuator being powered by an explosive charge and each pair being electrically connected uniquely to one of the momentum sensors.

Abstract: A method of allocating a cache used by a processor of a computer system between instructions and data is disclosed. Program instructions are loaded in the processor for monitoring relative usage of the cache by each value class and selecting a desired ratio of cache usage by the classes from among a plurality of available ratios, and cache blocks within the cache are evicted using a cache-replacement mechanism which restricts replacement of an evicted cache to a particular one of the classes of values (instruction or data) based on the desired ratio of cache usage. A multi-bit facility may be provided to indicate how to confine a selected victim to certain cache blocks, and the program instructions select the desired ratio of cache usage by setting the multi-bit facility. The cache-replacement mechanism can be a modified least recently used replacement mechanism. Different instruction/data ratios thereby may be provided, such as 1:1, 1:2, and 2:1.