Skip to main content

Page Load Time and the YSlow scalability model of web application performance

This content has been moved to http://computerperformancebydesign.com/why-is-my-web-app-running-slowly-part-1/.

Sorry for the inconvenience.

Comments

Popular posts from this blog

Inside the Windows Runtime, Part 2

As I mentioned in the previous post, run-time libraries in Windows provide services for applications running in User mode. For historical reasons, this run-time layer in Windows was always known as the Win32 libraries, even when these services are requested in the 64-bit OS in 32-bit mode. A good example of a Win32 run-time service is any operation that involves opening and accessing a file somewhere in the file system (or the network, or the cloud). A more involved example is the set of Win32 services an application needs to access to play an audio file, including understanding the specific audio file compressed format, and checking authorization and security.
For Windows 8, a portion of the existing Win32 services in Windows were ported to the ARM hardware platform.  The scope of the Win32 API is huge, and it was probably not feasible to convert all of it during the span of a single, time-constrained release cycle. Unfortunately, the fact that the new Windows 8 Runtime library encomp…

High Resolution Clocks and Timers for Performance Measurement in Windows.

Within the discipline of software performance engineering (SPE), application response time monitoring refers to the capability of instrumenting application requests, transactions and other vital interaction scenarios in order to measure their response times. There is no single, more important performance measurement than application response time, especially in the degree which the consistency and length of application response time events reflect the user experience and relate to customer satisfaction. All the esoteric measurements of hardware utilization that Perfmon revels in pale by comparison. Of course, performance engineers usually still want to be able to break down application response time into its component parts, one of which is CPU usage. Other than the Concurrency Visualizer that is packaged with the Visual Studio Profiler that was discussed in the previous post, there are few professional-grade, application response time monitoring and profiling tools that exploit the …

Why is my web app running slowly? -- Part 1.

This series of blog posts picks up on a topic I made mention of earlier, namely scalability models, where I wrote about how implicit models of application scalability often impact the kinds of performance tests that are devised to evaluate the performance of an application. As discussed in that earlier blog post, sometimes the influence of the underlying scalability model is subtle, often because the scalability model itself is implicit. In the context of performance testing, my experience is that it can be very useful to render the application’s performance and scalability model explicitly. At the very least, making your assumptions explicit opens them to scrutiny, allowing questions to be asked about their validity, for example.
The example I used in that earlier discussion was the scalability model implicit when employing stress test tools like HP LoadRunner and Soasta CloudTest against a web-based application. Load testing by successively increasing the arrival rate of customer r…