Soft timers is a new operating system facility that allows the efficient scheduling of software events at a granularity down to tens of microseconds. Soft timers can be used to avoid interrupts and reduce context switches associated with network processing without sacrificing low communication delays. Applications include rate-based pacing of packet transmissions and network polling.
For more details refer to our SOSP '99 paper available in gzip'd postscript and PDF. An extended version of the paper appeared in ACM Transactions on Computer Systems, August 2000.
The source code for an implementation of Soft timers is available.