On Sun, Apr 6, 2008 at 5:37 PM, dean gaudet <dean@arctic.org> wrote:
The MHZ measures time by gettimeofday( ), and
this assumes that the function gettimeofday( ) returns the actual
real-world time elapse in microseconds, instead of some scaled time.
What I mean here by scaled time is, Linux kernel keeps time by reading
a counter which is increased by one when an interrupt is generated
from a physical timer, and Linux defines the default HZ = 100 which
means an interrupt is generated every 10 milliseconds, but without
knowing which clock the physical timer is clocked at it is impossible
to correctly measure 10 milliseconds by the timer. Therefore, the
results from MHZ could be scaled? please correct me if I am wrong.
And, I believe this is the same case for Linux TSC (time stamp
counter), as the time constant of ~50ms is also measured by a
programmable interval timer which can also be scaled.
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