RFC: New event timers infrastructure

Alexander Motin mav at FreeBSD.org
Mon Jun 7 08:27:07 UTC 2010

Ed Schouten wrote:
> * Alexander Motin <mav at FreeBSD.org> wrote:
>> Most of x86 systems now has at least 4 types of event timers: i8254,
>> RTC, LAPIC and HPET. Respective code in kernel is very tangled, heavily
>> hardcoded and absolutely not scalable. I have reimplemented it, trying
>> to solve these issues.
> Just out of curiosity, how does this work relate to things like having a
> tickless kernel?

It is almost mandatory prerequisite. We can't do any fancy timer stuff
without unified timer API. Tsuyoshi Ozawa in his Dynamic Ticks work also
got to the same conclusion, but he was much less aggressive in rewriting
legacy code.

Alexander Motin

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