I'd like to make a modest proposal to get things started: Can we modify the various kernel entry points so that they don't acquire the giant lock(s) by default and instead parameterize the decision. In other words, somewhere associate a bit/flag with each trap/syscall, etc. that determines whether or not the lock is acquired. This would make incremental multithreading of the kernel easy, which I think is important. There's a fair bit of low-hanging fruit that this would enable us to pick. For example, there are a number of syscalls in the VM system that I could almost immediately enable multithreading of.