The speculative execution of critical sections, whether done using HTM via the transactional lock elision pattern or using a software solution such as STM or a sequence lock, has the potential to improve software performance with minimal programmer effort. The technique improves performance by allowing critical sections to proceed in parallel as long as they do not conflict at run time. In this...

Interprocess communication (IPC) is ubiquitous in today’s computing world. One of the simplest mechanisms for IPC is shared memory. We present a system that enhances the System V IPC API to support distributed shared memory by using speculations. Speculations provide performance improvements by enabling rollback of overly optimistic speculative executions. The paper describes a speculative tota...

The speculative circuit is a kind of special parallelizing circuits which could execute the sequential operations in parallel by breaking the dependencies between them through the prediction approach. That is, the consumer operations no longer needs to wait the computed results of the corresponding product ones by predicting them, so that the consumer operations can be executed with the corresp...

A processor with an explicit dataflow instruction-set architecture may be able to achieve performance comparable to a superscalar RISC processor, even on serial code. To achieve this, the dataflow processor must support speculative operation, especially speculative branches, and a pipeline with bypassing for serial code. This paper outlines a set of mechanisms to implement speculative operation...

Ambiguous beliefs may lead to speculative trade and speculative bubbles. We demonstrate this by showing that the classical Harrison and Kreps (1978) example of speculative trade among agents with heterogeneous beliefs can be replicated with agents having common ambiguous beliefs. More precisely, we show that the same asset prices and pattern of trade can be obtained in equilibrium with agents’ ...

Speculative statements communicating experimental findings are frequently found in scientific articles, and their purpose is to provide an impetus for further investigations into the given topic. Automated recognition of speculative statements in scientific text has gained interest in recent years as systematic analysis of such statements could transform speculative thoughts into testable hypot...

In a parallel graph reduction system, speculative evaluation can increase parallelism by performing potentially useful computations before they are known to be necessary. Speculative computations may be coded explicitly in a program, or they may be scheduled implicitly by the reduction system as idle processors become available. A general approach to both kinds of speculation incurs a great dea...

This article argues that commonly-studied techniques for speculative replication—such as prefetching or prepushing content to a location before it is requested there—are inherently unsafe: they pose unacceptable risks of catastrophic overload and they may introduce bugs into systems by weakening consistency guarantees. To address these problems, the article introduces SSR, a new, general archit...

Speculative multithreading is a technique that has been used to improve single thread performance. Speculative multithreading architectures for Chip multiprocessors (CMPs) have been extensively studied. But there have been relatively few studies on the design of speculative multithreading for simultaneous multithreading (SMT) processors. The current SMT based designs IMT [9] and DMT [2] use loa...

Transient execution attacks that exploit speculation have raised significant concerns in computer systems. Typically, branch predictors are leveraged to trigger mis-speculation transient attacks. In this work, we demonstrate a new class of speculation-based attack targets prediction unit (BPU). We find speculative resolution conditional branches (i.e., nested speculation) alter the states patte...