astronomy

Joel Emer

Joel Emer is a astronomy topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Joel Emer rather than just read about it. In short: Joel S. Emer (born March 2, 1954) is a pioneer in computer performance analysis techniques and a microprocessor architect.

Key takeaways

Joel Emer belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Joel Emer to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Joel Emer from memory before moving on to harder problems.

Reference excerpt

Joel S. Emer (born March 2, 1954) is a pioneer in computer performance analysis techniques and a microprocessor architect. He is currently a researcher at Nvidia, and a Professor of the Practice at MIT, and was formerly an Intel Fellow. He was the 2009 recipient of the Eckert–Mauchly Award.

Early life and education Born March 2, 1954, he received a bachelor's degree in electrical engineering in 1974 from Purdue University. 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 under the supervision of Prof. Edward S. Davidson.

Career His first job immediately after graduation was at Digital Equipment Corporation where he initially worked on VAX performance evaluation and then on Alpha 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 and Digital Equipment Corporation. He subsequently worked at Intel, 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, which was published in 1984 in the 11th International Symposium on Computer Architecture. That paper also contained the result that the VAX-11/780'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 (CPI), frequency and number of instructions to computer performance. Emer has also contributed to simultaneous multithreading (SMT), memory dependence prediction via store sets, and soft error analysis, and led the development of the Asim simulator. He was the 2009 recipient of the Eckert–Mauchly Award, for lifetime contributions in computer architecture. In 2020, Emer was elected as a member into the National Academy of Engineering for quantitative analysis of computer architecture and its application to architectural innovation in commercial microprocessors. He is currently a researcher at Nvidia, having joined in 2014. He is part of the company's Architecture Research group. He is also a Professor of the Practice at MIT.

See also List of fellows of the Association for Computing Machinery

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.

Illustrations

Worked examples

Example 1 — a first encounter with Joel Emer

Start with the simplest possible case. Write down what Joel Emer claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In astronomy, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Joel Emer before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Joel Emer ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Joel Emer

In research: Joel Emer appears in astronomy research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Joel Emer in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Joel Emer is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1954 births, American electrical engineers, Computer hardware engineers, so understanding it makes those chapters shorter.
In everyday life: Look for Joel Emer outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Joel Emer in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Joel Emer means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Joel Emer out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Joel Emer in simple terms?

Joel S. Emer (born March 2, 1954) is a pioneer in computer performance analysis techniques and a microprocessor architect.

Why does Joel Emer matter?

Because it connects several astronomy ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Joel Emer?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Joel Emer.