[$] ktask: optimizing CPU-intensive kernel work

As a general rule, the kernel is supposed to use the least amount of CPUtime possible; any time taken by the kernel is not available for theapplications the user actually wants to run. As a result, not a lot ofthought has gone into optimizing the execution of kernel-side work requiring largeamounts of CPU. But the kernel does occasionally have to take onCPU-intensive tasks, such as the initialization of the large amounts ofmemory found on current systems. The ktasksubsystem posted by Daniel Jordan is an attempt to improve how thekernel handles such jobs.