Emulating a processor's (limited) resources, including clock speed

Question

I would like a software environment in which I can test the speed of my software on hardware with specific resources. For example, how fast does this program run on an 800MHz x86 with 24 Mb of RAM, when my host hardware is a 3GHz quad core amd64 with 12GB of RAM? Emulators such as qemu make a great point of running "almost as fast" as the underlying hardware; I would like to make it run slower. Is there a way to do that?

Answer 1

I have never tried it, but perhaps you could achieve what you want to some extent by combining an emulator like QEMU or VirtualBox on Linux with something like this:

http://cpulimit.sourceforge.net/

If you can limit the CPU time available to the emulator you might be able to simulate the results of execution on a slower computer. Keep in mind, though, that this would only affect the execution speed (or so I hope, anyway).

The CPU instruction set and other system features would remain unchanged. This means that emulating a specific processor accurately would be difficult if not impossible.

In addition, using something like cpulimit, which works using SIGSTOP and SIGCONT to repeatedly stop/restart the emulator process might cause side-effects, such as timing inconsistencies, video display artifacts etc.