Re: do_fast_gettimeoffset on x86
H. Peter Anvin (hpa@transmeta.com)
4 Apr 1998 02:48:15 GMT
Followup to: <199804040237.TAA23211@nyx10.nyx.net>
By author: Colin Plumb <colin@nyx.net>
In newsgroup: linux.dev.kernel
>
> I was looking at the code, and it seems wrong. It implicitly assumes
> that the processor time stamp counter and the jiffies counter start
> at the same time. Even assuming a hard reset, the processor could
> have spent a very long time booting (or even hours in some other operating
> system before running loadlin) before jiffies got started.
>
> (It divides the rdtsc value by jiffies and uses that with the
> difference between the rdtsc value now and the value recorded by
> the last timer interrupt to compute the fraction of a jiffy
> we're currently at.)
>
> I have some ideas about fixing it, but is there anybody who "owns"
> that code and I should talk to before I start playing with it?
> (I also want to make it work with APM as much as possible.)
> --
> -Colin
>
I think Ulrich Windl is the current Linux time czar.
Ulrich: do you think this could account for some of the mysterious
time-skipping events we used to see?
-hpa
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