Messages in this thread |  | | Date | Fri, 30 Aug 2002 20:50:52 -0400 | From | Karim Yaghmour <> | Subject | Re: AGAIN: Re: gettimeofday clock jump bug (on AMD 756) |
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"Ph. Marek" wrote: > The difference is both times about 4295 seconds - so I think that the problem > has something to do with 2^32 microseconds.
This 2^32 jump is consistent with the jumps I saw.
I was discussing this issue with Richard Moore (IBM) a couple of weeks ago and he mentionned that they had seen a similar problem with OS/2. In that case, the problems were due to the time it took to read some timer register. In other words, there may be a short time-window where the values available are valid and nothing is garanteed if we exceed this time-window. (This is second hand and I may have misunderstood a couple of details, so I attached Richard so he can confirm/deny what I'm saying here.)
Linux reads the PIT (8253) every 10ms on a PC, so the question is: anyone know about 8253 reading deadlines ?
Karim
=================================================== Karim Yaghmour karim@opersys.com Embedded and Real-Time Linux Expert =================================================== - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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