Agner`s CPU blog

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Why is my computer so slow?
Author:  Date: 2009-11-28 08:54
I really like this article, and could not agree more with you regarding the spirit of optimal (or say "stable production mode") case scenario code testing. If I may, I would like to elaborate on your statements to include the "compounding" effect of this upon computer centers, such as core labs for medical imaging and pharmaceutical research and development.

In certain industries such as biotech/pharmaceutical, computer systems validation is required before any application can be utilized as a means to determine a clinical endpoint, or diagnosis.

Simply stated, computer system validation requires evidence of known outcomes with predictable and reproducible results. The basic components of validation include installation qualification, operational qualification, and performance qualification.

The point I want to make is that the last component, PQ is increasingly completed within a context of a poorly designed or developed user requirements specification document, OR within a testing framework that does not adequately "stress-test" the production environment. The analogy is very similar to the multiple operations of a computer system that aren't taken into account during design specifications, as you imply.

In this case, the "production environment" (e.g. a core lab containing many end-user systems, server(s), and the appropriate contingency systems and sub-systems), has a baseline idle time as well as peak periods. These peak periods are the time points that usually drive decisions for modifications to the environment to address bottlenecks.

If there were ways to better simulate these peak times in the PQ (including the points of your article, which I believe are overlooked), then the designers and developers could move to a more rational predictability of outcomes model, thus, User Acceptance Testing, for example, could play a greater role earlier in the code development process. Other benefits may include the optimization of the operating system(s) for the intended use of the computer while running the application.

Thanks for great information...

thread Why is my computer so slow? new - Agner Fog - 2009-10-06
reply Why is my computer so slow? - Declan Cooper - 2009-11-28
reply Why is my computer so slow? new - Igor Levicki - 2010-01-02
last replythread Why is my computer so slow? new - Shervin Emami - 2010-12-29
last reply Why is my computer so slow? new - Agner - 2010-12-29