Joel S. Emer (born March 2, 1954) is a pioneer in

computer performance In computing, computer performance is the amount of useful work accomplished by a computer system. Outside of specific contexts, computer performance is estimated in terms of accuracy, efficiency and speed of executing computer program instruction ...

analysis techniques and a

microprocessor A microprocessor is a computer processor (computing), processor for which the data processing logic and control is included on a single integrated circuit (IC), or a small number of ICs. The microprocessor contains the arithmetic, logic, a ...

architect. He is currently a researcher at

Nvidia Nvidia Corporation ( ) is an American multinational corporation and technology company headquartered in Santa Clara, California, and incorporated in Delaware. Founded in 1993 by Jensen Huang (president and CEO), Chris Malachowsky, and Curti ...

, and a Professor of the Practice at

MIT The Massachusetts Institute of Technology (MIT) is a private research university in Cambridge, Massachusetts, United States. Established in 1861, MIT has played a significant role in the development of many areas of modern technology and sc ...

, and was formerly an

Intel Intel Corporation is an American multinational corporation and technology company headquartered in Santa Clara, California, and Delaware General Corporation Law, incorporated in Delaware. Intel designs, manufactures, and sells computer compo ...

Fellow. He was the 2009 recipient of the

Eckert–Mauchly Award The Eckert–Mauchly Award recognizes contributions to digital systems and computer architecture. It is known as the computer architecture community’s most prestigious award. First awarded in 1979, it was named for John Presper Eckert and Joh ...

Early life and education

Born March 2, 1954, he received a bachelor's degree in electrical engineering in 1974 from

Purdue University Purdue University is a Public university#United States, public Land-grant university, land-grant research university in West Lafayette, Indiana, United States, and the flagship campus of the Purdue University system. The university was founded ...

. He received his master's degree in 1975 from Purdue. In 1979, Emer received his Ph.D. degree in electrical engineering from the

University of Illinois, Urbana-Champaign The University of Illinois Urbana-Champaign (UIUC, U of I, Illinois, or University of Illinois) is a public land-grant research university in the Champaign–Urbana metropolitan area, Illinois, United States. Established in 1867, it is the fou ...

under the supervision of Prof.

Edward S. Davidson Edward S. Davidson is a professor emeritus in Electrical Engineering and Computer Science at the University of Michigan, Ann Arbor. Research interests His research interests include computer architecture, pipelining theory, parallel processing, pe ...

Career

His first job immediately after graduation was at

Digital Equipment Corporation Digital Equipment Corporation (DEC ), using the trademark Digital, was a major American company in the computer industry from the 1960s to the 1990s. The company was co-founded by Ken Olsen and Harlan Anderson in 1957. Olsen was president until ...

where he initially worked on

VAX VAX (an acronym for virtual address extension) is a series of computers featuring a 32-bit instruction set architecture (ISA) and virtual memory that was developed and sold by Digital Equipment Corporation (DEC) in the late 20th century. The V ...

performance evaluation and then on

Alpha Alpha (uppercase , lowercase ) is the first letter of the Greek alphabet. In the system of Greek numerals, it has a value of one. Alpha is derived from the Phoenician letter ''aleph'' , whose name comes from the West Semitic word for ' ...

performance evaluation. As a consequence of his performance evaluation work, he became a pioneer in the quantitative approach to computer architecture. He contributed a variety of research and advanced development ideas that were incorporated into various VAX and Alpha processor designs, In conjunction with the development and application of various performance analysis techniques. He worked at

Compaq Compaq Computer Corporation was an American information technology, information technology company founded in 1982 that developed, sold, and supported computers and related products and services. Compaq produced some of the first IBM PC compati ...

and

. He subsequently worked at

, where he was Director of Microarchitecture Research, out of the Massachusetts Microprocessor Design Center (MMDC). He was named an Intel Fellow in 2001. He is well known, along with his co-author Douglas W. Clark, for a seminal paper on the quantitative analysis of processor architectures,A Characterization of Processor Performance in the VAX-11/780
Joel S. Emer, Douglas W. Clark, 1984, lEEE which was published in 1984 in the 11th

International Symposium on Computer Architecture The International Symposium on Computer Architecture (ISCA) is an annual academic conference on computer architecture, generally viewed as the top-tier in the field. Association for Computing Machinery's Special Interest Group on Computer Archit ...

. That paper also contained the result that the

VAX-11/780 The VAX-11 is a discontinued family of 32-bit superminicomputers, running the Virtual Address eXtension (VAX) instruction set architecture (ISA), developed and manufactured by Digital Equipment Corporation (DEC). Development began in 1976. In ad ...

's performance was actually 0.5 MIPS instead of 1 MIPS as was previously claimed by DEC. That result helped popularize what Clark called the iron law of processor performance that related

cycles per instruction In computer architecture, cycles per instruction (aka clock cycles per instruction, clocks per instruction, or CPI) is one aspect of a processor's performance: the average number of clock cycles per instruction for a program or program fragmen ...

(CPI), frequency and number of instructions to

. Emer has also contributed to

simultaneous multithreading Simultaneous multithreading (SMT) is a technique for improving the overall efficiency of superscalar CPUs with hardware multithreading. SMT permits multiple independent threads of execution to better use the resources provided by modern proces ...

(SMT),

memory dependence prediction Memory dependence prediction is a technique, employed by high-performance out-of-order execution microprocessors that execute memory access operations (loads and stores) out of program order, to predict true dependencies between loads and stores at ...

via store sets, and

soft error In electronics and computing, a soft error is a type of error where a signal or datum is wrong. Errors may be caused by a defect, usually understood either to be a mistake in design or construction, or a broken component. A soft error is also a ...

analysis, and led the development of the Asim simulator. He was the 2009 recipient of the

, for lifetime contributions in computer architecture. In 2020, Emer was elected as a member into the

National Academy of Engineering The National Academy of Engineering (NAE) is an American Nonprofit organization, nonprofit, NGO, non-governmental organization. It is part of the National Academies of Sciences, Engineering, and Medicine (NASEM), along with the National Academ ...

for quantitative analysis of computer architecture and its application to architectural innovation in commercial microprocessors. He is currently a researcher at

, having joined in 2014. He is part of the company's Architecture Research group. He is also a Professor of the Practice at

References

;Notes * Emer, Joel S.; Clark, Douglas W. (1984). "A characterization of processor performance in the VAX-11/780". ''Proceedings of the 11th Annual International Symposium on Computer Architecture''. pp. 301–310. {{DEFAULTSORT:Emer, Joel Living people 1954 births Purdue University alumni University of Illinois Urbana-Champaign alumni Digital Equipment Corporation people Intel people 2004 fellows of the Association for Computing Machinery Fellows of the IEEE Computer hardware engineers American electrical engineers Place of birth missing (living people) Nvidia people

Early life and education

Career

See also

References