Matt Dillon’s been working on this patch, described as so:

“These are dyamic[sic] interrupt-driven timers. They replace the old fixed periodic ‘hardclock’ interrupt that exists now and allow per-cpu multiple periodic or one-shot timer interrupts to be registered with the system. Systimers operate outside the MP lock, so any code developed to use it has to be MP safe. Systimers are intended to be able to make use of per-cpu timers (e.g. LAPIC), when available, and will eventually be augmented to use them.”

It also has the added bonus of making nanosleep() very accurate.