Abstract: A novel trace cache design and organization to efficiently store and retrieve multi-path traces. A goal is to design a trace cache, which is capable of storing multi-path traces without significant duplication in the traces. Furthermore, the effective access latency of these traces is reduced.

Abstract: A memory storage structure includes a memory storage device, and a first meta-structure having a first size and operating at a first speed. The first speed is faster than a second speed for storing meta-information based on information stored in a memory. A second meta-structure is hierarchically associated with the first meta-structure. The second meta-structure has a second size larger than the first size and operates at the second speed such that faster and more accurate prefetching is provided by coaction of the first and second meta-structures. A method is provided to assemble the meta-information in the first meta-structure and copy this information to the second meta-structure, and prefetching the stored information from the second meta-structure to the first meta-structure ahead of its use.

Abstract: A memory storage structure includes a memory storage device, and a first meta-structure having a first size and operating at a first speed. The first speed is faster than a second speed for storing meta-information based on information stored in a memory. A second meta-structure is hierarchically associated with the first meta-structure. The second meta-structure has a second size larger than the first size and operates at the second speed such that faster and more accurate prefetching is provided by coaction of the first and second meta-structures. A method is provided to assemble the meta-information in the first meta-structure and copy this information to the second meta-structure, and prefetching the stored information from the second meta-structure to the first meta-structure ahead of its use.

Abstract: A hardware monitor is used to monitor the sequence of instructions executed during a miss cluster. The monitor groups each cache miss into a miss cluster, and the miss penalty associated with each cluster is determined by identifying a set of instructions that were executed during the miss cluster. The finite cache running time is then calculated for the set of instructions that occurred during the miss cluster. Additionally, an infinite cache running time is determined for the same set of instructions that occurred during the miss cluster, where the infinite cache running time is the time needed to execute this set of instructions in the absence of any miss. The cost of the miss cluster is then calculated by measuring the difference between the finite cache running time and the infinite cache running time.

Abstract: A method for supporting and tracking a plurality of stores in an out-of-order processor run by a predetermined program includes executing a plurality of instructions on the processor, each instruction including an address from which data is to be loaded and a plurality of memory locations from which load data is received, determining inputs of the instructions, determining a function unit on which to execute the instructions; storing the plurality of instructions in both a Retirement Store Queue (RSTQ) and a Forwarding Store Queue (FSTQ), the RSTQ comprising a list of the plurality of stores and the FSTQ comprising a list of respective addresses of the plurality of stores, allowing the plurality of stores to be stored in the plurality of memory locations, and allowing the plurality of stores to forward the load data only after the instructions have determined that the predetermined number of the stores has completed the series of the execution processes.

Abstract: A method for supporting and tracking a plurality of loads in an out-of-order processor being run by a program includes executing instructions on the processor, the instructions including an address from which data is to be loaded and memory locations from which load data is received, determining inputs of the instructions, determining a function unit on which to execute the instructions, storing the plurality of instructions in both a LRQ and a LIP queue, the LRQ comprising a list of the plurality of stores and the LIP comprising a list of respective addresses of the plurality of loads, dividing the LIP into a set of congruence classes, each holding a predetermined number of the loads, allowing the loads to be stored in the memory locations, snooping the load data, and allowing a plurality of snoops to selectively invalidate the load data from snooped addresses so as to maintain sequential load consistency.

Abstract: A method for reducing the number of load instructions in the load reorder queue (LRQ) that are searched when a load instruction is executed by a processor, including dispatching the load instructions; inserting the load instructions in the LRQ in program order; clearing a load received data field; executing the load instructions; checking load reorder queue (LRQ) entries; re-executing the load instruction of the matching LRQ entry; continuing execution; getting the load data; setting the load received data field; comparing a load sequence number (LSQN) of each load instruction to a snoop_safe register contents; ANDing all the load received data bits if the LSQN is greater in magnitude to the snoop_safe; setting the snoop_safe register to the LSQN of the load instruction; searching the LRQ entry; and setting a load_peril_snoop register to the LRQ index value where the first load instruction younger to the snoop_safe was found.

Abstract: A method for reducing the number of times in-flight loads must be searched by store instructions in a multi-threaded processor including freezing load issue for a thread t_old for a number of cycles; rejecting a t_new load instruction; sending notification to the rest of the processor that the t_new load instruction has been rejected; snooping a load reorder queue (LRQ) of a t_old for any load which comes from a cache line L accessed by the load instruction and then forces such loads to be re-executed; and changing ownership of line L to thread t_new.

Abstract: A system to prevent livelock. An outcome of an event is predicted to form an event outcome prediction. The event outcome prediction is compared with a correct value for a datum to be accessed. An instruction is appended with a real event outcome when the outcome of the event is mispredicted to form an appended instruction. A prediction override bit is set on the appended instruction. Then, the appended instruction is executed with the real event outcome.

Abstract: A device for controlling power parameters in a microprocessor includes a resource activation control unit for controlling the maximum power of the microprocessor and two or more resources. The resource activation control unit controls the activation of the resources such that the consumed and dissipated power of the microprocessor does not exceed a power bound which is configurable to a predetermined value below the maximum power.

Abstract: An integrated circuit (IC) including unit power control, leakage reduction circuit for controllably reducing leakage power with reduced LdI/dt noise in the IC and, an activity prediction unit invoking active/dormant states in IC units. The prediction unit determines turn on and turn off times for each IC unit. The prediction unit controls a supply voltage select circuit selectively passing a supply voltage to a separate supply line at the predicted turn on time and selectively blocking the supply voltage at the predicted turn off time.

Abstract: Arrangements and methods for providing cache management. Preferably, a buffer arrangement is provided that is adapted to record incoming data into a first cache memory from a second cache memory, convey a data location in the first cache memory upon a prompt for corresponding data, in the event of a hit in the first cache memory, and refer to the second cache memory in the event of a miss in the first cache memory.

Abstract: A method for handling permanent and transient errors in a microprocessor is disclosed. The method includes reading a scalar value and a scalar operation from an execution unit of the microprocessor. The method further includes writing a copy of the scalar value into each of a plurality of elements of a vector register of a Single Instruction Multiple Data (SIMD) unit of the microprocessor and executing the scalar operation on each scalar value in each of the plurality of elements of the vector register of the SIMED unit using a vector operation. The method further includes comparing each result of the scalar operation on each scalar value in each of the plurality of elements of the vector register and detecting a permanent or transient error if all of the results are not identical.

Abstract: A novel trace cache design and organization to efficiently store and retrieve multi-path traces. A goal is to design a trace cache, which is capable of storing multi-path traces without significant duplication in the traces. Furthermore, the effective access latency of these traces is reduced.

Abstract: A hardware based method for determining when to migrate cache lines to the cache bank closest to the requesting processor to avoid remote access penalty for future requests. In a preferred embodiment, decay counters are enhanced and used in determining the cost of retaining a line as opposed to replacing it while not losing the data. In one embodiment, a minimization of off-chip communication is sought; this may be particularly useful in a CMP environment.

Abstract: A memory storage structure includes a memory storage device, and a first meta-structure having a first size and operating at a first speed. The first speed is faster than a second speed for storing meta-information based on information stored in a memory. A second meta-structure is hierarchically associated with the first meta-structure. The second meta-structure has a second size larger than the first size and operates at the second speed such that faster and more accurate prefetching is provided by coaction of the first and second meta-structures. A method is provided to assemble the meta-information in the first meta-structure and copy this information to the second meta-structure, and prefetching the stored information from the second meta-structure to the first meta-structure ahead of its use.

Abstract: An integrated circuit (IC) including unit power control, leakage reduction circuit for controllably reducing leakage power with reduced LdI/dt noise in the IC and, an activity prediction unit invoking active/dormant states in IC units. The prediction unit determines turn on and turn off times for each IC unit. The prediction unit controls a supply voltage select circuit selectively passing a supply voltage to a separate supply line at the predicted turn on time and selectively blocking the supply voltage at the predicted turn off time.

Abstract: A two level branch history table (TLBHT) is substantially improved by providing a mechanism to prefetch entries from the very large second level branch history table (L2 BHT) into the active (very fast) first level branch history table (L1 BHT) before the processor uses them in the branch prediction process and at the same time prefetch cache misses into the instruction cache. The mechanism prefetches entries from the very large L2 BHT into the very fast L1 BHT before the processor uses them in the branch prediction process. A TLBHT is successful because it can prefetch branch entries into the L1 BHT sufficiently ahead of the time the entry is needed. This feature of the TLBHT is also used to prefetch instructions into the cache ahead of their use. In fact, the timeliness of the prefetches produced by the TLBHT can be used to remove most of the cycle time penalty incurred by cache misses.

Abstract: A mechanism is described that prefetches instructions and data into the cache using a branch instruction as a prefetch trigger. The prefetch is initiated if the predicted execution path after the branch instruction matches the previously seen execution path. This match of the execution paths is determined using a branch history queue that records the branch outcomes (taken/not taken) of the branches in the program. For each branch in this queue, a branch history mask records the outcomes of the next N branches and serves as an encoding of the execution path following the branch instruction. The branch instruction along with the mask is associated with a prefetch address (instruction or data address) and is used for triggering prefetches in the future when the branch is executed again. A mechanism is also described to improve the timeliness of a prefetch by suitably adjusting the value of N after observing the usefulness of the prefetched instructions or data.