I am trying to get accurate time stamps during usb isoc-read completion
routines. Looking at the darwin source code for GetBusFrameNumber() I see
that no effort is made to guard for the possibility that my thread is
preempted between the time the AbsoluteTime is measured, and the current bus
frame number is obtained.
I presume it is possible to be preempted in the kernel, and depending on the
system load, I presume its possible to be in the ready queue for some
considerable time.
If I want super-accurate time stamps, should I repeat calls to
GetBusFrameNumber() until I can be sure that the call wasn't interrupted?
Thanks,
Chris
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