Messages in this thread | | | Date | Wed, 11 Apr 2001 13:43:31 -0500 (CDT) | From | Oliver Xymoron <> | Subject | Re: No 100 HZ timer ! |
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On Mon, 9 Apr 2001, Alan Cox wrote:
> > > Its worth doing even on the ancient x86 boards with the PIT. > > > > Note that programming the PIT is sloooooooow and doing it on every timer > > add_timer/del_timer would be a pain. > > You only have to do it occasionally. > > When you add a timer newer than the current one > (arguably newer by at least 1/2*HZ sec)
That's only if we want to do no better than the current system. We'd want a new variable called timer_margin or something, which would be dependent on interrupt source and processor, and could be tuned up or down via sysctl.
> When you finish running the timers at an interval and the new interval is > significantly larger than the current one.
Make that larger or smaller. If we come out of a quiescent state (1 hz interrupts, say) and start getting 10ms timers, we want to respond to them right away.
> Remember each tick we poke the PIT anyway
We could also have a HZ_max tunable above which we would not try to reprogram the interval. On older systems, this could be set at 100-200HZ...
-- "Love the dolphins," she advised him. "Write by W.A.S.T.E.."
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