EOS' is a fully functioning preemptive real time kernel originally developed for the Infineon XC167 microcontroller. Performance summary: A typical context switch will take about 100[µs] at 40[Mhz], when all tasks have a stack of 256 bytes.
Version 2.0 includes the following modifications:
* Task stack snapshots allows the creation of a copy of a task's stack for a later restore. Note: This will not preserve system resources (running timers, mutexes etc.) that a task owns when the snapshot is made. * Added flag timers: timers that increment a user provided counter to indicate that they have expired instead of invoking a callback. Useful for systems where, for example, interrupts must be very fast (note: normal timers invoke their callback on interrupt context). An expiration of a timer can then set a flag for the main program, where an operation will take place after leaving interrupt context. * Enhanced performance due to code optimization.
see sourceforge.net/.../