Tickless system?

Matthew Dillon dillon at apollo.backplane.com
Tue Oct 9 16:58:02 PDT 2007

:"...further development like full tickless systems, where the time
:slice is controlled by the scheduler, variable frequency profiling,
:and a complete removal of jiffies in the future."
:AFAIK this kind of thing is orthogonal to the goals of this project,
:but it still seems an interesting idea -- one which might eventually
:be of interest here.  Dunno.
:Any opinions on this tickless idea, pros/cons/relevance?

    Well, DragonFly already uses its systimer API for nearly all timer
    events in the system.  There is still a base tick but, for example,
    the scheduler has its own periodic event.  The base tick in DragonFly
    drives process statistics, the 'ticks' counter, and the seconds counter,
    and that's pretty much it.

    The real issue here is probably cutting down on timer events when a
    system is idle - almost certainly to improve the efficiency of
    virtualized systems.  I think it's a separate problem space.  It would
    certainly be possible for our various subsystems to detect an idle
    condition and stop requesting periodic timeouts in that situations.
    I'm not sure its worth doing, though.

					Matthew Dillon 
					<dillon at backplane.com>

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