boost::asio threadpool vs. io_service_per_cpu design

Question

Currently I´m not sure, I try to make a high-performance server, I got a 6Core CPU, so if I would use the "io_service_per_cpu" design, I have 6 io_service´s.

I already heard that the threadpool design isn´t the best one, but I´m not sure about that.

What knowledge do you have? Someone already made a Stress test with each, or something else?

Answer 1

In my experience it is vastly easier to approach asynchronous application design with the following order:

1. single thread and a single io_service
2. multiple threads, each invoking io_service::run() from a single io_service. Use strands for handlers that require access to shared data structures.
3. io_service per cpu

The motivation for changing between each of these designs should be done after profiling your application. Note that the HTTP Server 2 example only shows how to use an io_service per CPU, it does not show you when or why to use such a design.

Answer 2

Another good way to approach this: start up multiple copies of your process and bind each one to a different core using your OS'es. For FreeBSD, use cpuset. The OS is going to do a better job than any userland code will. Then you need to use an external load balancer to distribute load across your server instances. Extra points for binding a NIC interrupts to a particular CPU.