john stultz wrote:
On Wed, 2005-08-24 at 17:24 -0700, George Anzinger wrote:
CLOCK_TICK_RATE is used by the kernel to compute LATCH, TICK_NSEC and
tick_nsec. This latter is used to update xtime each tick. TICK_NSEC is
then used to compute (at compile time) the conversion constants needed
to convert to/from jiffies from/to timespec and timeval (and others).
The problem is that, if the timer being used is either Cyclone or HPET,
the wrong CLOCK_TICK_RATE is used.
Err, the Cyclone does not generate interrupts. So this issue does not
affect those systems.
As for the HPET, it sets its own interrupt frequency based off of
KERNEL_TICK_USEC (which you're right, isn't quite what is used in the
jiffies conversions). Would it be easier to just adjust that value to
use ACTHZ or CLOCK_TICK_RATE?
If you want to take that approach you would want the HPET to interrupt
every TICK_NSEC nanoseconds, that being what xtime is pushed by each tick.
--
George Anzinger [email protected]
HRT (High-res-timers): http://sourceforge.net/projects/high-res-timers/
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