Methods and apparatus for implementing partial and start-over threads in a kernel of an operating system are disclosed. In a computing system having at least one CPU, registers for executing threads, and memory, a method for executing a partial thread includes executing a first thread in the registers, initiating an interrupt event that signals the activation of another thread, saving a first portion of registers to a memory location, wherein a second portion of the registers is unsaved, the first portion including information associated with the first thread, executing in the registers, the another thread, and conducting further computing system operations. Additionally, conducting further computing system operations can include restoring the saved first portion of registers from the memory location to the registers and resuming execution of the first thread. Also, another embodiment incorporates the foregoing method into a computer device.