TSOtool

Hangal et. al. [3] have developed a procedure to check if an instance of the execution of a shared memory multiprocessor program, is consistent with the Total Store Order (TSO) memory consistency model. They also devised an algorithm based on this procedure with time complexity O(n 5), where n is the total number of instructions in the program. Roy et. al. [6] have improved the implementation of the procedure and achieved O(n 4) time complexity. We have identified the bottleneck in these algorithms as a graph problem of independent interest, called implied-set closure (ISC) problem. In this paper we propose an algorithm for ISC problem and show that using this algorithm, Hangal's consistency checking procedure can be implemented with O(n 3) time complexity. We also experimentally show that the new algorithm is significantly faster than Roy's algorithm.

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A Better x86 Memory Model: x86-TSO

Owens

Sarkar

Sewell

2009

Lecture Notes in Computer Science

323

271

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Abstract. Real multiprocessors do not provide the sequentially consistent memory that is assumed by most work on semantics and verification. Instead, they have relaxed memory models, typically described in ambiguous prose, which lead to widespread confusion. These are prime targets for mechanized formalization. In previous work we produced a rigorous x86-CC model, formalizing the Intel and AMD architecture specifications of the time, but those turned out to be unsound with respect to actual hardware, as well as arguably too weak to program above. We discuss these issues and present a new x86-TSO model that suffers from neither problem, formalized in HOL4. We believe it is sound with respect to real processors, reflects better the vendor's intentions, and is also better suited for programming. We give two equivalent definitions of x86-TSO: an intuitive operational model based on local write buffers, and an axiomatic total store ordering model, similar to that of the SPARCv8. Both are adapted to handle x86-specific features. We have implemented the axiomatic model in our memevents tool, which calculates the set of all valid executions of test programs, and, for greater confidence, verify the witnesses of such executions directly, with code extracted from a third, more algorithmic, equivalent version of the definition.

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TSOtool

Cited by 48 publications

References 12 publications

Efficiently and Completely Verifying Synchronized Consistency Models

Efficiently and Completely Verifying Synchronized Consistency Models

Implied Set Closure and Its Application to Memory Consistency Verification

A Better x86 Memory Model: x86-TSO

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