Performance and energy efficiency in simple simultaneous multithreading processor cores

Simultaneous multithreading, where instructions from different threads share processor resources, has shown promise in delivering high throughput with little area and power overhead. We compare where in the performance energy-efficiency space alternative simple simultaneous multithreading configurations lie, leveraging standard industry tools to estimate area and power from high level hardware descriptions. We find sharing function units among threads can improve energy efficiency over duplicating the function unit set for each thread. A good choice for the number of threads sharing a function unit ensures the function unit is not overloaded. Sharing front-end pipeline logic does not improve performance or energy efficiency over either duplicating the full pipeline or just duplicating the front-end pipelines for each thread. Different arbitration policies for use of function units do not impact performance much, but they do have a large impact on the power of the core, so the simplest arbitration policy should be used to maximize energy efficiency. Operand bypassing, an obvious optimization for a pipeline which does not share function units, is not obviously better when function units are shared, improving performance at the cost of reduced energy efficiency.

Department dc:contributor.department

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

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2010

Author dc:creator

• Uhler, Richard Stephen

Advisor dc:contributor.advisor

• Jack B. Dennis.

• 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/1721.1/60191

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/60191