Abstract: In one embodiment, the present invention includes a method for providing a cache block in an exclusive state to a first cache and providing the same cache block in the exclusive state to a second cache when cores accessing the two caches are executing redundant threads. Other embodiments are described and claimed.

Abstract: Methods of operating two or more devices in lockstep by generating requests at each device, comparing the requests, and forwarding matching requests to a servicing node are described and claimed. A redundant execution system using the methods is also described and claimed.

Abstract: Embodiments of apparatuses and methods for reducing the uncorrectable error rate in a lockstepped dual-modular redundancy system are disclosed. In one embodiment, an apparatus includes two processor cores, a micro-checker, a global checker, and fault logic. The micro-checker is to detect whether a value from a structure in one core matches a value from the corresponding structure in the other core. The global checker is to detect lockstep failures between the two cores. The fault logic is to cause the two cores to be resynchronized if there is a lockstep error but the micro-checker has detected a mismatch.

Abstract: A network may include an interconnection system which allows packets to transit from various sources to various destinations under control of routers. The routers may determine a transit time of packet transit from various sources to a given destination. This information may be used to detect a hot spot within the network. Other embodiments are described and claimed.

Abstract: A method and apparatus for protecting a TLB's VPN from soft errors is described. On a TLB lookup, the incoming virtual address is used to CAM the TLB VPN. In parallel with this CAM operation, parity is computed on the incoming virtual address for the possible page sizes supported by the processor. If a matching VPN is found in the TLB, its payload is read out. The encoded page size is used to select which of the set of pre-computed virtual address parity to compare with the stored parity bit in the TLB entry. This has the advantage of removing the computation of parity on the TLB VPN from the critical path of the TLB lookup. Instead it is now in the TLB fill path.

Abstract: A technique for demand-based error correction. More particularly, at least one embodiment of the invention relates to a technique to reduce storage overhead of cache memories containing error correction codes (ECC) while maintaining substantially the same performance of the cache.

Abstract: A technique to detect errors in a computer system. More particularly, at least one embodiment of the invention relates to using redundant virtual machines and comparison logic to detect errors occurring in input/output (I/O) operations in a computer system.

Abstract: A method for a fault free store data path in a software implementation of redundant multithreading environments is described. In one embodiment, after a check is performed by a hardware/software checker, the processor still needs to ensure that the data just checked reaches protected memory without any faults. The present implementation provides sufficient redundant information along the path of a store from register read to commit, such that it may detect any single bit upset error in the path.

Abstract: A method, an apparatus and a system for a computing system implements a technique known as cache push that enhances a single writer invalidation protocol with the ability to optionally push data into another processor's cache without changing the memory consistency model being utilized by the method, apparatus and system.

Abstract: A technique to reduce false error detection in microprocessors. A pi bit is propagated with an instruction through an instruction flow path. When a parity error is detected, the pi bit is set, instead of raising a machine check exception. Upon reaching a commit point, the processor can determine if the instruction was on a wrong path.

Abstract: A technique to reduce false error detection in microprocessors within a redundant multi-threaded computing environment. A pi bit is propagated with at least two instructions through an instruction flow path. Results of executing the instruction are compared to see if an error has occurred and if so, the pi bits are examined to determine which instruction contains the error.

Abstract: A memory element which includes a family of fault-tolerant storage elements using complementary metal-oxide-semiconductor (CMOS) technology is provided. The memory element provides arbitrary levels of redundancy, allowing the tolerance of multiple single event upsets due to particle hits. The memory element may be used in memory arrays such as caches and register files, and clocked registers and latches found in data path and control structures.

Abstract: In one embodiment, the present invention includes a system, which may be a multiprocessor system having multiple nodes, each with a processor and a cache. The system may include a directory stored in a memory that includes entries having coherency information. At least one of the nodes may be configured to detect an error in an entry of the directory based on a coherency protocol and a state of a status indicator and presence vector of the entry, and without the storage of error correction or parity information in the entry. In some embodiments, the node may correct the error using state information obtained from other nodes.

Abstract: Methods and apparatus to reduce power consumption in arbiters of interconnection routers are described. In one embodiment, an arbiter may be turned off for a select number of clock cycles if no arbitration is to be performed on the corresponding buffer.

Abstract: A multithreaded architecture is disclosed for managing external memory updates for fault detection in redundant multithreading systems using speculative memory support. In particular, a method provides input replication of load values on a SRT processor by using speculative memory support to isolate redundant threads form external updates. This method thus avoids the need for dedicated structures to provide input replication.

Abstract: A memory element which includes a family of fault-tolerant storage elements using complementary metal-oxide-semiconductor (CMOS) technology is provided. The memory element provides arbitrary levels of redundancy, allowing the tolerance of multiple single event upsets due to particle hits. The memory element may be used in memory arrays such as caches and register files, and clocked registers and latches found in data path and control structures.

Abstract: Methods and apparatus to efficiently detect faults are described. In an embodiment, an encoded value may be generated based on a portion of an instruction address and a portion of a corresponding result value. The encoded value may be used to determine whether an entry corresponding to the encoded value is absent from a screening storage unit. Other embodiments are also described.

Abstract: A technique to reduce false error detection in microprocessors by tracking instructions neutral to errors. As an instruction is decoded, an anti-pi bit is tagged to the decoded instruction. When a parity error is detected, an instruction queue first checks if the anti-pi bit is set. If the anti-pi bit is set, then instruction is neutral to errors, and the pi bit need not be set. Prefetch, branch predict hint and NOP are types of instructions that are neutral to errors.

Abstract: An apparatus includes a buffer that collects store instruction information associated with one or more processes. The collected store instruction information includes data and addresses where the data are to be stored. The apparatus also includes a buffer control that drains the buffer of store instructions associated with a first process before it collects store instructions associated with a second process.

Abstract: Log-based hardware recovery. A checkpointed state of a system includes both architectural register values and memory. The checkpoint consists of a copy of the architectural register file values at the time the checkpoint is generated. An ordered log of non-deterministic events is maintained so that the responses can be repeated to simulate a complete checkpoint for error recovery purposes. When a processor detects an error, the processor reloads the state from the last checkpoint and repeats the non-deterministic events from the log.