# Blog Archives

## Go Guerrill… R on Your Data in August

July 5, 2010
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Only one month to go! Register now for the Guerrilla Data Analysis Techniques (GDAT) class to be held during the week of August 9-13, 2010. The focus will be on using R and the PDQ-R for computer performance analysis and capacity planning.(Click on t...

## Prime Parallels for Load Balancing

July 5, 2010
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Having finally popped the stack on computing prime numbers with R in Part II and Part III, we are now in a position to discuss their relevance for computational scalability.My original intent was to show how poor partitioning of a workload can defeat the linear scalability expected when full parallelism is otherwise attainable, i.e., zero contention (σ) and...

## Linear Modeling in R and the Hubble Bubble

June 22, 2010
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Here is a scatter plot with the coordinate labels deliberately omitted. Figure 1. Do you see any trends? How would you model these data? It just so happens that this scatterplot is arguably the most famous scatterplot in history. One aficionado, writing more than forty years after its publication, commented skeptically :" data points were consequently spread all over the ...

## Playing with Primes in R (Part II)

June 17, 2010
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Popping Part III off the stack—where I ended up unexpectedly discovering that the primes and primlist functions are broken in the schoolmath package on CRAN—let's see what prime numbers look like when computed correctly in R. To do this, I've had to roll my own prime number generating function.Personalizing primes in RFor what I want to show, I mostly...

## Primes in R (Part III): Schoolmath is Broken!

June 13, 2010
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Here we are in Part III. Wait!? What happened to Parts I and II? Well, I started to write an article about Amdahl's law, parallelism and prime numbers, but found myself buried three levels deep trying to resolve problems with prime numbers in R. My normal inclination is to use Mathematica for such things, but I happened to already...

## Go Guerrill-R on Your Data in August

June 8, 2010
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Guerrill-R, get it? Register now for the Guerrilla Data Analysis Techniques (GDAT) class to be held during the week of August 9-13, 2010. The focus will be on using R and the PDQ-R for computer performance analysis and capacity planning.(Click on the...

## Simulating a Queue in R

May 30, 2010
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In the GCaP class earlier this month, we talked about the meaning of the load average (in Unix and Linux) and simulating a grocery store checkout lane, but I didn't actually do it. So, I decided to take a shot at constructing a discrete-event simulatio...

## Load Testing Think Time Distributions

May 20, 2010
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One of my gripes about some commercial load testing tools is that they only provide a think time distribution (Z) that is equivalent to uniform variates in the client-script. If you want some other distribution, you have to code it and debug it yoursel...

## Emulating Internet Traffic in Load Tests

May 15, 2010
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One of the recurring questions in the GCaP class last week was: How can we make web-application load tests more representative of real Internet traffic? The sticking point is that conventional load-test simulators like LoadRunner, JMeter, and httperf, ...

## Significant Figures in R and Rounding

April 16, 2010
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This is a follow-on to my previous post about determining significant digits, or sigdigs, in performance and capacity planning calculations. Once we know how to do that, inevitably we will be faced with rounding the result of a calculation to the least...