WMM : a resilient Weak Memory Model

A good memory model should have a precise definition that can be understood by any computer architect readily. It should also be resilient in the sense that it should not break when new microarchitecture optimizations are introduced to improve single-threaded performance. We introduce WMM, a new weak memory model, which meets these criteria. WMM permits all load-store reorderings except a store is not allowed to overtake a load. WMM also permits both memory dependency speculation and load-value prediction. We define the operational semantics of WMM using a novel conceptual device called invalidation buffer, which achieves the effect of out-of-order instruction execution even when instructions are executed in-order and one-at-a-time. We show via examples where memory fences need to be inserted for different programming paradigms. We highlight the differences between WMM and other weak memory models including Release Consistency and Power. Our preliminary performance evaluation using the SPLASH benchmarks shows that WMM implementation performs significantly better than the aggressive implementations of SC. WMM holds the promise to be a vendor-independent stable memory model which will not stifle microarchitectural innovations.

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2016

Author dc:creator

• Zhang, Sizhuo

Advisor dc:contributor.advisor

• Arvind.

• Electrical Engineering and Computer Science.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/103667

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/103667