Blog Archives

Emulating Internet Traffic in Load Tests

May 15, 2010
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Emulating Internet Traffic in Load Tests

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, ...

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Significant Figures in R and Rounding

April 16, 2010
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Significant Figures in R and Rounding

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...

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Significant Figures in R and Info Zeros

April 11, 2010
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Significant Figures in R and Info Zeros

The other day, I stumbled upon the signif function in R, so I thought I'd take a look at what it does and compare it with some results discussed in Chap. 3 "Damaging Digits in Capacity Calculations" of my GCaP book, viz., Example 3.5 on page 31. The m...

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PDQ 5.0 Test Suite or … How I Spent My Weekend

June 29, 2009
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PDQ 5.0 Test Suite or … How I Spent My Weekend

I was planning to blog about the amazing time I had at Velocity 2009 last week, when this landed in my mailbox (edited for space and privacy): Subject: Seeking help with PDQ-R ...Date: Thu, 25 Jun 2009 15:51:21 -0500My name is James and I've be...

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August Guerrilla Class: Using R for Performance Analysis

June 29, 2009
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August Guerrilla Class: Using R for Performance Analysis

Registrations are still open for the Guerrilla Data Analysis Techniques (GDAT) class being held August 10-14, 2009. The focus will be on using R and the new release of PDQ-R for performance analysis and capacity planning.All Guerrilla classes are hel...

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Negative Scalability Coefficients in Excel

May 12, 2009
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Negative Scalability Coefficients in Excel

Recently, several performance engineers, who have been applying my universal scalability law (USL) to their throughput measurements, reported a problem whereby their Excel spreadsheet calculations produced a negative value for the coherency parameter (...

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Barry3-Apdex Also Lives in R

April 17, 2009
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Barry3-Apdex Also Lives in R

As a by-product of my presentation on the Apdex Index at the NorCal CMG meeting, back in February, Guerrilla graduate, Stephen O'Connell, went off and did an implementation in R. You can read about it in this month's CMG MeasureIT and download his R-s...

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PDQ 5.0 is on the Launch Pad

April 4, 2009
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PDQ 5.0 is on the Launch Pad

PDQ (Pretty Damn Quick) major release 5.0 is on the launch pad at Cape SourceForge. Because of a potential collision with the North Korean ICBM/satellite launch, we won't be filling the main liquid-hydrogen tank until next week (we don't want PDQ blame...

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Modern Microprocessor MIPS

April 2, 2009
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Modern Microprocessor MIPS

The question of how modern microprocessors compare with mainframe processors of yore, arises from time to time. The vernacular rate metric that has persisted for a long time (long in the history of computers, that is) is MIPS. Whether you approve of M...

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Streaming Hadoop Data Into R Scripts

March 23, 2009
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Streaming Hadoop Data Into R Scripts

Along the lines of Mongo Measurement Requires Mongo Management, the HadoopStreaming package on CRAN provides utilities for applying R scripts to Hadoop streaming. Hadoop is used on Amazon's EC2.

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