peterjeremy at optushome.com.au
Wed May 6 10:13:07 UTC 2009
Currently, FreeBSD uses the LAPIC timer to derive both hardclock()
and statclock()/profclock() if it exists, otherwise it uses the
8254 and RTC. This presents a problem for using C3 - which stops
the LAPIC clock.
Some time ago, ariff@ produced a patch to work around a similar
problem with C1E on some AMD Turion CPUs:
A better solution would seem to be to use a HPET periodic timer. Is
there a particular reason why code to (at least optionally) support
HPET as the timer interrupt hasn't been written? Looking back through
the archives, pkh@ has made disparaging remarks about the actual
usefulness of HPET (as against the Intel documentation) but I can't
find anything that actually talks about using it.
Note that supporting HPET as a timer source would provide at least
some of the infrastructure that will be needed for a future tickless
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