I want to know how many resources (MySQL time, CPU usage, bandwidth, etc.) will use my system with a certain number of API calls per second.
One API call gets the parameters in PHP, do from 1 to 5 SQL queries and returns a XML file.
How I can do that? Any idea of a formula or something?
Use something like httperf to make constant load to your server like for example 10 req/sec Then you will have value how much your server is loaded at 10 req/sec, just scale that value up/down.
Of course, testing it "right" is very hard, as some calls will be shorter than other, so you have to know load profile of each req. type and how often each type of request is used.... or replay "production" traffic
