Raw throughput of a WordPress web site and influence of cpu and memory on the front
In order to evaluate the expected performance of a WordPress web site, I first decided to focus on a single front and to play with the CPU and MEMORY resources of the front.
To be sure that no other bottlenecks appear (such as the database server resources -CPU, MEMORY, IO – or the network resources), I was continually checking the performance counters on the database server and on the front server with commands such as iostat, vmstat, top and iftop for the network during the workload. After a while, I found the perfect command dstat that shows all counters for CPU, IO and MEMORY from just one command line.
To quickly evaluate the speed (throughput) of the web site, I decided to use the apache tool ab that gives a very useful indicator in req/s.