Abstract: Provided is a method for uniquely masking addressing to the cache memory for each user, thereby reducing risk of a timing attack by one user on another user. The method comprises assigning a first mask value to the first user and a second mask value to the second user. The mask values are unique to one another. While executing a first instruction on behalf of the first user, the method comprises applying the first mask value to set selection bits in a memory address accessed by the first instruction. While executing a second instruction on behalf of the second user, the method comprises applying the second mask value to set selection bits in the memory address accessed by the second instruction. The result offers an additional level of security between users as well as reducing the occurrence of threads or processes contending for the same memory address.

Abstract: In a computer system with caching, memory transactions can retrieve and store groups of lines. Coherency states are maintained for groups of lines, and for individual lines. A single coherency transaction, and a single address transaction, can then result in the transfer of multiple lines of data, reducing overall latency. Even though lines may be transferred as a group, the lines can subsequently be treated separately. This avoids many of the problems caused by long lines, such as increased cache-to-cache copy activity.

Abstract: A cache memory system can determine that an entry is stale if the entry has not been accessed or modified for a predetermined time. If an entry is stale, the entry may be preemptively evicted. The predetermined time is made dynamically variable. A computer system can adjust the time to optimize a measure of performance. In a specific example, evicted lines are temporarily stored in an eviction queue. The time is adjusted to be as short as possible without substantially increasing the number of lines that must be recalled from the eviction queue.

Abstract: In one embodiment, the present invention is directed to a processor that comprises an instruction pipeline for executing processor instructions wherein the processor instructions define a memory access size and a cache memory for storing cache lines in a plurality of memory banks that have a block size that is greater than the memory access size, the cache memory including mapping logic for storing contiguous groups of bits, of size equal to the memory access size, in different ones of the plurality of memory banks.

Abstract: In processing an instruction request, the invention determines whether the request is speculative or not based upon a bit field within the instruction. If the request is speculative, bus congestion and/or target memory is assessed for conditions and a decision is made, based on the conditions, as to whether or not to process the request. To facilitate the invention, certain bit fields within the instruction are encoded to identify the request as speculative or not. Additional bit fields may define a priority of a speculative request to influence the decision to process as based on the conditions. CPU architectures incorporating prefetch logic may be modified to recognize instructions encoded with speculation and priority identification fields to implement the invention in existing systems. Other logic, e.g., bus controllers and switches, may similarly process speculative requests to enhance system performance.

Abstract: A digital image capture device including circuits capable of measuring the distance between the image capture device and an imaged object allows the capture of three-dimensional data of the surface of the object facing the image capture device. The distance data is obtained by the addition of a flash unit, and very high resolution timers to multiple pixels within the image capture device to measure the time required for the flash to reflect from the object. Since the speed of light is constant, the distance from the flash to the object to the image capture device may be calculated from the delay for the light from the flash to reach the device. Multiple pixels may be used to construct a three-dimensional model of the surface of the object facing the image capture device. Multiple images including distance data may be taken in order to generate a complete three-dimensional model of the surface of the object.

Abstract: A networked system includes a fault tolerant storage system (FTSS) having an interconnection fabric that also carries network traffic. A plurality of servers are coupled to an FTSS via an FTSS interconnection fabric. As soon as a packet is received from a sending node, the packet is committed to reliable, persistent, and fault-tolerant storage media within the FTSS, and will not be lost. If the destination node is one of the servers coupled to the FTSS, the FTSS can send an acknowledgment to the sending node guaranteeing delivery to the destination node, even though the destination node has not yet received the packet. The packet is then transmitted to the receiving node, with the receiving node sending an acknowledgment to the FTSS when the packet has been received successfully.

Abstract: A system and method for analyzing the effectiveness of a computer cache memory. A bus with memory transactions is monitored. A subset of addresses, along with associated transaction data, on the bus is captured and stored in a memory. The captured addresses are applied to a software model of a computer cache. The capture process is repeated multiple times, each time with a different subset of the address space. Statistical estimates of hit rate and other parameters of interest are computed based on the software model. Multiple cache configurations may be modeled for comparison of performance. Alternatively, a subset of addresses along with associated transaction data is sent to a hardware model of a cache. The contents of the hardware model are periodically dumped to memory or statistical data may be computed and placed in the memory. Statistical estimates of hit rate and other parameters of interest are computed based on the contents of the memory.

Abstract: A method and apparatus pass messages between server and client applications using a fault tolerant storage system (FTSS). The interconnection fabric that couples the FTSS to the computer systems that host the client and server applications may also be used to carry messages. A networked system capable of hosting a distributed application includes a plurality of computer systems coupled to an FTSS via an FTSS interconnection fabric. The FTSS not only processes file-related I/O transactions, but also includes several message agents to facilitate message transfer in a reliable and fault tolerant manner. The message agents include a conversational communication agent, an event-based communication agent, a queue-based communication agent, a request/reply communication agent, and an unsolicited communication agent. The highly reliable and fault tolerant nature of the FTSS ensures that the FTSS can guarantee delivery of a message transmitted from a sending computer system to a destination computer system.

Abstract: A cache system improves performance by limiting the number of dirty entries in a cache. The cache system may be further improve performance by limiting the number of dirty entries in a cache that might be subject to a cache-to-cache transfer. In a first example, a cache system counts the total number of dirty entries in the cache and preemptively evicts at least one dirty entry when the count exceeds a predetermined threshold. In a variation, a cache system counts dirty cache entries that result from a cache-to-cache transfer, and evicts at least one dirty entry that results from a cache-to-cache transfer when the number exceeds a predetermined threshold. For either system, the predetermined threshold may be dynamically varied to determine a value that optimizes performance.

Abstract: A cache system improves performance by limiting the number of dirty entries in a cache. The cache system may further improve performance by limiting the number of dirty entries in the cache that might be subject to a cache-to-cache transfer. In a first example, a cache system counts the total number of dirty entries in the cache and preemptively evicts at least one dirty entry when the count exceeds a predetermined threshold. In a variation, a cache system counts dirty cache entries that result from a cache-to-cache transfer, and evicts at least one dirty entry that results from a cache-to-ache transfer when the number exceeds a predetermined threshold.

Abstract: A multiprocessor computer system continues operation after the failure of a cooling device coupled to a central processing unit (CPU). In accordance with the present invention, an impending failure of a cooling device is detected, and all user and operating system processes are moved from the affected CPU coupled to the failing cooling device to one or more other CPUs. The system state is then altered so that interrupts are no longer received and processed by the affected CPU, and all memory caches associated with the affected CPU are flushed back to main memory to ensure cache coherency. At this point, the CPU is either powered-down, or placed in a low-power mode that allows the CPU to operate without the cooling device, while the processes that were removed from the suspended CPU continue executing on other CPUs.

Abstract: In a method of managing memory, a plurality of check values are generated from contents of memory. Each check value is associated with a respective page in a memory system in a data structure. The data structure is searched for a candidate page having identical content to a requesting page in the memory system by utilizing a check value of the requested page in the search.

Abstract: In a computer system with caching, memory transactions can retrieve and store groups of lines. Coherency states are maintained for groups of lines, and for individual lines. A single coherency transaction, and a single address transaction, can then result in the transfer of multiple lines of data, reducing overall latency. Even though lines may be transferred as a group, the lines can subsequently be treated separately. This avoids many of the problems caused by long lines, such as increased cache-to-cache copy activity.

Abstract: In a computer system with caching, memory transactions can retrieve and store groups of lines. Coherency states are maintained for groups of lines, and for individual lines. A single coherency transaction, and a single address transaction, can then result in the transfer of multiple lines of data, reducing overall latency. Even though lines may be transferred as a group, the lines can subsequently be treated separately. This avoids many of the problems caused by long lines, such as increased cache-to-cache copy activity. In one alternative, when a cache memory requests a group of lines, and when the group of lines is partially owned by another cache memory, then the requesting cache receives fewer than all the lines in the requested group.

Abstract: A device and method for collecting data on which lines are being shared in a multiprocessor system having cache memories is described. In the present invention, a sample arm register observes a local channel, such as a bus, for key events. Upon waiting a certain number of events, the sample arm register arms a sample register. Once armed the sample register will latch the next qualified address of the data being collected. The sampled data is then stored in memory. Post processing software will read the data from memory. The samples are then analyzed to correlate them with such things as locations and data structures in the system. This helps dynamically optimize the work load to reduce shared dirty line traffic.

Abstract: A system whereby vendors of computer systems may advantageously utilize the processing capability of the computers in these systems after the systems have been sold. The system provides computer services via a network of computers which have been sold with an agreement from the buyers thereof to permit the seller to conditionally utilize the computers subsequent to the sale thereof.

Abstract: A lower level cache detects when a line of memory has been evicted from a higher level cache. The lower level cache stores the address of the evicted line. When the system bus is idle, the lower level cache initiates a transaction causing all higher level caches to invalidate the line. The lower level cache then places the line into a special state. If a line in the special state is evicted from the lower level cache, the lower level cache knows that the line is not cached at a higher level, and therefore a back-invalidate transaction is not needed.

Abstract: A cache system improves performance by limiting the number of dirty entries in a cache. The cache system may further improve performance by limiting the number of dirty entries in the cache that might be subject to a cache-to-cache transfer. In a first example, a cache system counts the total number of dirty entries in the cache and preemptively evicts at least one dirty entry when the count exceeds a predetermined threshold. In a variation, a cache system counts dirty cache entries that result from a cache-to-cache transfer, and evicts at least one dirty entry that results from a cache-to-cache transfer when the number exceeds a predetermined threshold.

Abstract: In processing an instruction request, the invention determines whether the request is speculative or not based upon a bit field within the instruction. If the request is speculative, bus congestion and/or target memory is assessed for conditions and a decision is made, based on the conditions, as to whether or not to process the request. To facilitate the invention, certain bit fields within the instruction are encoded to identify the request as speculative or not. Additional bit fields may define a priority of a speculative request to influence the decision to process as based on the conditions. CPU architectures incorporating prefetch logic may be modified to recognize instructions encoded with speculation and priority identification fields to implement the invention in existing systems. Other logic, e.g., bus controllers and switches, may similarly process speculative requests to enhance system performance.