1. A system, comprising: a context holder that stores privileged hardware states of a user mode schedulable (UMS) thread; a primary thread that enters kernel mode via a system call; and a user mode scheduler that replaces first context information of a kernel portion of the primary thread with second context information from a kernel portion of the UMS thread, wherein the primary thread loads the stored privileged hardware states into the kernel portion of the primary thread after the replacement of the first context information with the second context information.