Computer Systems Performance Modeling

August 25th, 2020

“Long ago, far away
Things like that don’t happen
No more, nowadays, do they?”
(1962) “Long Ago, Far Away” – Bob Dylan

Computer Systems Performance Modeling, which Professor K.M. Chandy and I wrote in 1978-9, previously published by Pearson Education, Inc. is now out of print. We are making PDF copies of lightly edited versions available under a Creative Commons license.

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Remembering RESQ

August 25th, 2020

    T-Shirt Martin Reiser made for me

Ed MacNair and I published two books based on The Research Queueing Package, RESQ. Those books, previously published by Pearson Education, Inc. are now out of print. We are making PDF copies of lightly edited versions available under a Creative Commons license, at Simulation of Computer Communication Systems and Elements of Practical Performance Modeling. Though we have written two prior articles about RESQ history1,2, those did not cover subsequent development, so another recap seems appropriate now.


In the early 1970s, when computing capabilities were tiny, tiny, tiny compared to even a cell phone today, and those resources were typically time-shared across multiple users, queueing network models became a primary tool to analyze and improve system performance. Queueing models had been studied for years before regarding communication systems and other systems, but networks of queues seemed especially apropos for understanding time-sharing systems. Several of my fellow graduate students and I, students of Professors J.C. Browne and K.M. Chandy, decided we needed a queueing network simulation environment to accompany models solved by numerical and approximate methods. We defined and implemented QSIM3 for this purpose, including abstractions such as “passive servers”.

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[koko] continuing to under-react to COVID-19

July 18th, 2020

“The only thing I knew how to do
Was to keep on keepin’ on like a bird that flew”
(1975) “Tangled Up In Blue” – Bob Dylan

At a March 12 AIX alumni pizza lunch I told a friend something like “We’re probably over-reacting to this, but better to over-react than under-react. This will probably better prepare us for some future pandemic.”

tl;dr In 2020 hindsight, like almost everybody, I was under-reacting. Read the rest of this entry »

[koko] the Ides of March 2020

March 15th, 2020

“Genghis Khan and his brother Don
Could not keep on keepin’ on”
(1971) “You Ain’t Goin’ Nowhere” – Bob Dylan

In spite of the pandemic, I feel blessed today. Blessed that my mother was a public health nursing professor, who taught me hygiene and many other useful practices especially useful now. Blessed that my father was a public health statistician, that my sister is a family practice physician, that my graduate studies and early professional life engaged me in probability, modeling, and simulation. I feel better prepared than many to understand and adjust to this new reality.

COVID spread graph

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[tbt] childhood amateur radio projects

November 21st, 2019

6M converter

As part of redecorating our house and trying to organize my chaotic archives, I stumbled across a paper copy of The Radio Handbook (William Orr, Editor) 17th Edition. While in junior high school I built several projects out of The Handbook, probably the 16th Edition. [This paper copy is dated 1967, so too recent. The Radio Handbook (William Orr, Editor) 15th Edition 1959 doesn’t seem to have my projects, but I haven’t obtained 16th edition PDF.] Read the rest of this entry »