摘要:
Systems and methods of managing threads provide for supporting a plurality of logical threads with a plurality of simultaneous physical threads in which the number of logical threads may be greater than or less than the number of physical threads. In one approach, each of the plurality of logical threads is maintained in one of a wait state, an active state, a drain state, and a stall state. A state machine and hardware sequencer can be used to transition the logical threads between states based on triggering events and whether or not an interruptible point has been encountered in the logical threads. The logical threads are scheduled on the physical threads to meet, for example, priority, performance or fairness goals. It is also possible to specify the resources that are available to each logical thread in order to meet these and other, goals. In one example, a single logical thread can speculatively use more than one physical thread, pending a selection of which physical thread should be committed.
摘要:
A system and method for compensating for branching instructions in trace caches is disclosed. A branch predictor uses the branching behavior of previous branching instructions to select between several traces beginning at the same linear instruction pointer (LIP) or instruction. The fetching mechanism of the processor selects the trace that most closely matches the previous branching behavior. In one embodiment, a new trace is generated only if a divergence occurs within a predetermined location. A divergence is a branch that is recorded as following one path (i.e. taken) and during execution follows a different path (i.e. not taken).
摘要:
Embodiments of the present invention relate to a memory management scheme and apparatus that enables efficient cache memory management. The method includes writing an entry to a store buffer at execute time; determining if the entry's address is in a first-level cache associated with the store buffer before retirement; and setting a status bit associated with the entry in said store buffer, if the address is in the cache in either exclusive or modified state. The method further includes immediately writing the entry to the first-level cache at or after retirement when the status bit is set; and de-allocating the entry from said store buffer at retirement. The method further may comprise resetting the status bit if the cacheline is allocated over or is evicted from the cache before the store buffer entry attempts to write to the cache.
摘要:
Methods and apparatus for restoring a meta predictor system upon detecting a branch or binary misprediction, are disclosed. An example apparatus may include a base misprediction history register to store a set of misprediction history values each indicating whether a previous branch prediction taken by a previous branch instruction was predicted correctly or incorrectly. The apparatus may comprise a meta predictor to detect a branch misprediction of a current branch prediction based at least in part on an output of the base misprediction history register. The meta predictor may restore the base misprediction history register based on the detecting of the branch misprediction. Additional apparatus, systems, and methods are disclosed.
摘要:
Techniques for vector completion mask (VCM) handling are provided. A data structure includes a mask field for each operand of a particular operation. A processor attempts to execute the operation with multiple operands, which are identified in the data structure by the mask fields. If operands are successfully retrieved for execution with the operation, then the corresponding mask field within the data structure is cleared. The processor can reset if any field remains set within the data structure and can re-process the operation with operands that were not previously handled with the operation.
摘要:
In one embodiment, the present invention includes a method for executing an operation on low order portions of first and second source operands using a first execution stack of a processor and executing the operation on high order portions of the first and second source operands using a second execution stack of the processor, where the operation in the second execution stack is staggered by one or more cycles from the operation in the first execution stack. Other embodiments are described and claimed.
摘要:
A method is disclosed. The method includes scheduling a load operation at least twice the size of a maximum access supported by a memory device, dividing the load operation into a plurality of separate load operation segments having a size equivalent to the maximum access supported by the memory device, and performing each of the plurality of load operation segments. A further method is disclosed where a temporary register is used to minimize the number of memory accesses to support unaligned accesses.
摘要:
In one embodiment, a method for flow optimization and prediction for vector streaming single instruction, multiple data (SIMD) extension (VSSE) memory operations is disclosed. The method comprises generating an optimized micro-operation (μop) flow for an instruction to operate on a vector if the instruction is predicted to be unmasked and unit-stride, the instruction to access elements in memory, and accessing via the optimized μop flow two or more of the elements at the same time without determining masks of the two or more elements. Other embodiments are also described.
摘要:
A technique to perform three-source instructions. At least one embodiment of the invention relates to converting a three-source instruction into at least two instructions identifying no more than two source values.
摘要:
Microarchitecture policies and structures partition execution resource clusters. In disclosed microarchitecture embodiments, micro-operations representing a sequential instruction ordering are partitioned into a two sets. To one set of micro-operations execution resources are allocated from a cluster of execution resources that can perform memory access operations but not branching operations. To the other set of micro-operations execution resources are allocated from a cluster of execution resources that can perform branching operations but not memory access operations. The first and second sets of micro-operations may be executed out of sequential order but are retired to represent their sequential instruction ordering.