5 replies to this topic

[questioner1]

i haven't found any real article on the internet that describes everything that affects the performance of a computer program.
trade-offs between ram and cpu. what cache memory is, etc.
I would really like to know what all the different components of a computer are, public vs local vars, relating to speed etc. up till now i just haven't thought about it, and just declared vars all over the place.

i know the basic stuff, like more statements takes more cpu time, and referencing reading vars from other objects takes more time than reading a local var, or a var from the same object.
i want to go proffesional, so please don't try to give me simplified information.

thank you.

[WingedPanther]

There are a LOT of variables that impact a program's performance. A simple database program will involve:
1) local processing
2) network traffic to the database server
3) server load
4) database optimization for the query in question
5) database size
6) hard drive speed on both systems
7) RAM on both systems
8) CPU speed on both systems
9) number of processors/cores

etc.
etc.
etc.

The nature of the application is a huge factor in determining the resources it uses, and thus what resources may impact performance.

[questioner1]

i see.
how slow is does user input compared to reading RAM etc?
i heard it's very slow, but how slow?

[WingedPanther]

Reading RAM is measured in milliseconds. User input can, for some applications, be measured in hours. An example: I may leave FireFox running on my computer at work and go home. It then sits there for as much as 30 hours waiting for me to do something.

[questioner1]

oh, no i dont mean that. i mean when you press a button, how much time does it take for the cpu to do something with it? how much will one button press slow down your computer?

[WingedPanther]

It depends on what is associated with the button press. I have programs where a button press triggers 3 hours of 100% CPU usage. The time to register the button press is probably not noticeable by a human under normal CPU loads.