Adjust the handling the various timer frequencies when using the lapic

timer.  Previously, the various divisors were fixed which meant that while
it gave somewhat reasonable stathz, etc. at hz=1000, it went off the rails
with any other hz value.  With these changes, we now pick a lapic timer hz
based on the value of hz.  If hz is >= 1500, then the lapic timer runs at
hz.  If 1500 hz >= 750, we run the lapic timer at hz * 2.  If hz < 750, we
run at hz * 4.  We compute a divider at runtime to make stathz run as close
to 128 as we can since stathz really wants to be run at something close to
that frequency.  Profiling just runs on every clock tick.  So some examples:

With hz = 100, the lapic timer now runs at 400 instead of 2000.  stathz
will be 133, and profhz = 400.  With hz = 1000 (default), the lapic timer
is still at 2000 (as it is now), stathz is at 133 (as it is now), and
profhz will be 2000 (previously 666).

MFC after:	2 weeks

0 files changed, 0 insertions, 0 deletions