The Queueing Knee, Part 1

The “knee” in the queueing theory response time curve is a topic of some debate in the performance community. Some say “the knee is at 75% utilization; everyone knows that.” Others say “it depends.” Others say “there is no knee.”

Depending on the definition, there is a knee, but there are several definitions and you may choose the one you want. In this post I’ll use a definition proposed by Cary Millsap: the knee is where a line from the origin is tangent to the queueing response time curve. The result is a function of the number of service channels, and although we may argue about the topics in the preceding paragraph and whether this is the right definition, it still serves to illustrate important concepts.

knee

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A Great Mid-Priced Stereo System

You probably know that I like to be pretty minimalistic, and don’t accumulate a lot of “stuff” in my life. Yet for the few material things I value, I try to find the sweet spot: quality above average, price no higher than needed.

Music is one of the things I care a lot about: I have bought thousands of CDs. But I also value when my music sounds as good as possible. I treated myself to an upgraded stereo system so I’d enjoy better audio quality. Here’s my current system.

stereo

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6 Steps to Better Security and Privacy

I wrote previously about securing your digital life. Technology and digital threats are advancing so fast that we’re almost inevitably all going to be attacked in some way. Here are a few more steps I’ve taken recently.

Blue Marbles

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Remembering Alan And Harry

Harry Weller died suddenly this week. Harry was one of the best venture capital investors in history. He led NEA’s investment in my company, VividCortex. Harry was an advocate and mentor to me, but he was more: in both life and death, he reminded me of Alan Rimm-Kaufman, a boss and mentor who died a handful of years ago.

Alan Rimm-Kaufman and Harry Weller

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Excel Hacks To Ignore Missing Data

I’ve done quite a bit of work with Excel over the last few years, and I’ve found a couple of recurring problems when there’s missing or error data in ranges. I’ve had to work around this enough times that I thought it was worth sharing the solutions I’ve used.

Beautiful green bird eating orange peels

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Forestry, a Static Site CMS

Forestry is a content management system that runs in your browser. On the backend, it integrates with a static site generator such as Hugo, letting you edit your static website in your browser just like any other content management system. I am writing this blog post with it on my iPad, using voice dictation.

forest

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The Response Time Stretch Factor

Computer systems, and for that matter all types of systems that receive requests and process them, have a response time that includes some time waiting in queue if the server is busy when a request arrives. The wait time increases sharply as the server gets busier. For simple systems there is a simple equation that describes this exactly, but for more complicated systems this equation is only approximate. This has rattled around in my brain for a long time, and rather than keeping my notes private I’m sharing them here (although since I’m still trying to learn this stuff I may just be putting my ignorance on full display).

Hockey-Stick Curve

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The Square Root Staffing Law

The square root staffing law is a rule of thumb derived from queueing theory, useful for getting an estimate of the capacity you might need to serve an increased amount of traffic.

Square Root Staffing Law

The square root staffing law is designed to help with capacity planning in what’s called the QED regime, which tries to balance efficiency with quality of service. Capacity planning is a set of tradeoffs: for best quality of service, you must provision lots of spare capacity (headroom), but that’s wasteful. For best efficiency, you minimize idle capacity, but then quality of service becomes terrible.

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Life on Mobile: The Last Mile on iPad

I wrote previously about how I run much of my life on iPhone/iPad, and how I switched from Android to iPhone. Why do I still have a laptop, if I can do so much on mobile devices? What holds me back?

jet engine

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Life on Mobile: The iPhone Apps And Services I Use

In my last post I talked about the transition from Android to iOS and some of the experiences I had during that journey. Once I switched, I found a rich ecosystem of iPhone and iPad apps I use daily. Some of them are central to my workflow and professional life, and I use them across all my devices, including my laptop/desktop systems. In this post I’ll talk about those apps and how they enable me to run the bulk of my life (and my company) on a phone screen.

Torx Bits

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Life on Mobile: From Android to iOS

I’ve been living an increasingly mobile life lately, by which I mean laptops aren’t my sole or even primary computing device anymore. For the last two years I’ve been doing more computing on mobile devices than laptops or desktops. I’m writing this post on my iPad Pro. At the same time, I’m a heavy user of old-school technologies: command line, LaTeX, terminal-based editors, etc. I find it interesting that my life is increasingly possible to run on a mobile device, while at the same time my laptop remains absolutely indispensable. As I thought about this, I found myself organizing the last few years’ worth of lessons into distinct categories, which I’m strangely compelled to write into blog posts. So, here goes! In the first edition we will follow Baron on his adventures as he transitions from Android to iOS.

Metamorphosis

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Five Surprising Secrets of People Who Always Win

Are you a winner? Or are you going to let life get you back on your heels and make you into a failure? Because remember, if you lose, it means you’re a loser. By definition.

Winners

Here’s the surprising truth about what winners do and how they do it, and how you can too.

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The Four Types of Core Intellectual Property

If you ask people what their company’s core intellectual property is, my guess is most responses would focus on technical things such as trade secrets, recipes, source code, and algorithms. But I’ve come to believe this definition doesn’t encompass a company’s most valuable intellectual property at all.

blueprint

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Meeting The Challenges of Monitoring In The Cloud

I’ll be visiting MIT’s Tang Center on October 10 in Boston to talk about monitoring. Join me!

Tang

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Gluten

I’m not saying I’m gluten-sensitive. I just know that when I eat things like pizza, bread, pasta, or the like, I suffer. And gluten-free alternatives are disgusting. But I’ve figured out how to make the breads I love, such as pancakes, waffles, and muffins, without pain. Here’s my recipe.

Stacked Rocks

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What Women Tell Me

Someday I’ll write a companion blog post about what men tell me, but today I want to write about what I’ve learned by listening to women over the last few years.

Why do I care? It’s because women tell me things that men rarely, sometimes never tell me. I failed to notice this for the longest time, but when I started to, I decided to sit up and listen, hard.

Disclaimer: I’m not saying that men don’t care or talk about these types of things. In fact, many of these episodes of sexism came to me through a man’s Twitter post. BUT WOMEN RETWEETED IT TO ME.

Gramophone

I will now present things I have heard only or mostly from women, in many cases without attribution to the original author or the woman who drew this to my attention (because I think that’s the safest thing to do).

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Cursive Writing

When I was a child, I learned to write in cursive using the A Beka Books homeschooling curriculum. I resumed journaling in cursive a couple years ago, after decades of writing with block letters (printing).

Cursive

Although my motivation to relearn cursive was to make my daily journaling more special by setting it apart, I didn’t simply regain what I had forgotten. I found something entirely new, and learned a great deal I’d never known before.

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Just Enough Better

What makes a product, project, or application become popular? People talk a lot about attributes such as stickiness, virality, addictive qualities, and gamification.

I don’t pretend to have a universal answer, but many of the successful things I’ve been involved with worked well because they were just enough better for people to care a lot.

mousetrap

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Intent

One of the core teachings of Drucker’s classic “Managing Oneself” is to form hypotheses about what you’ll do well or poorly, and then observe the outcomes. By repeatedly practicing this, you learn what you’re good and bad at.

Compass

At some point I noticed that I sometimes wasn’t certain why I failed or succeeded. As I’ve explored this more deeply in the last few years, I’ve come to see that the biggest factor in my success or failure is often the clarity of my purpose itself.

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Why I'm Not Waiting To Prioritize Diversity

I have a vacant board seat at VividCortex, and I’m making diversity one of my priorities as I begin to search. I’ve discussed this with a range of people over the last several months. Nearly everyone has asked me to clarify what I’m trying to achieve, and why. Some have challenged me to defend why I believe diversity is a must-have at this stage of VividCortex’s growth. In the end, it’s my job to make the call. I’ve decided that diversity is a priority (not the sole priority, but a priority) now, not later. Here’s why—and here’s how I’m following through on that decision.

Board

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