Speculating on Speculative Execution

Speculative Execution based on Value Prediction

Speculative Execution for Information Agents

Practical deployments of information agents can suffer from sub-optimal performance and scalability for a number of reasons. In the case of web-based information integration, for example, data sources are remote and their latency can have a substantial effect on overall execution performance. Scalability can also be poor, since concurrent queries can cause multiple, simultaneous remote data ret...

Spectre Attacks: Exploiting Speculative Execution

Modern processors use branch prediction and speculative execution to maximize performance. For example, if the destination of a branch depends on a memory value that is in the process of being read, CPUs will try guess the destination and attempt to execute ahead. When the memory value finally arrives, the CPU either discards or commits the speculative computation. Speculative logic is unfaithf...

Data and Control Speculative Execution

Control and data flow speculation can improve processor performance through increased ILP. First it is demonstrated how aggressive speculation on both control decisions and data values can produce parallelism in a simple “sequential” problem. It is then shown through simulation that a speculative architecture can extract parallelism from more complex code examples. Finally a discussion about th...

Future Branches { beyond Speculative Execution

The performance and hardware complexity of superscalar architectures is hindered by conditional branch instructions. When conditional branches are encountered in a program, the instruction fetch unit must rapidly predict the branch predicate and begin speculatively fetching instructions with no loss of instruction throughput. Speculative execution increases hardware cost, since speculative inst...