1. A method, comprising: switching a primary user portion of a primary thread to a user mode schedulable (UMS) user portion of a UMS thread in a user mode, each of the primary thread and the UMS thread including a corresponding user portion for execution in the user mode and a corresponding kernel portion for execution in a kernel mode; executing the UMS user portion of the UMS thread via the primary user portion in the user mode; transferring the primary thread into the kernel mode via an implicit switch; and executing a UMS kernel portion of the UMS thread in the kernel mode using current context information of a primary kernel portion of the primary thread.