LinuxDevices.com: Design of a Fully Preemptable Linux Kernel [white paper]

“MontaVista has developed a hard real-time fully preemptable
Linux kernel, based on Linux kernel 2.4. The preemptable kernel has
the potential to dramatically improve application responsiveness of
the Linux kernel, while fully preserving the standard Linux
programming model. The current prototype of the preemptable Linux
kernel (for IA32/X86 platforms) is available for ftp download, at

“The preemption model used is to allow the kernel to be
preempted at any time when it is not locked. This is very different
from the model where preemption is actively requested by the
currently executing code. Using this model, when an event occurs
that causes a higher priority task to be executable, the system
will preempt the current task and run the higher priority task. Of
course, there are times when this should not be done.”