Re: question about use of x86 tsc in do_fast_gettimeoffset

Charles 'Buck' Krasic (
03 Nov 1999 09:10:30 -0800


Doh. I forgot how unsigned math works.

It doesn't matter if the tsc wraps after setting last_tsc_low. The
subtraction, eax -= last_tsc_low, will still yield the right result.
As long as the tsc wrap hasn't occurred more than once. That could
only happen if the timer interrupt didn't run for 2^32 cycles (about
10s on my machine).

-- Buck

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