Messages in this thread | | | Date | Tue, 30 Oct 2001 10:21:25 +0200 | From | Ville Herva <> | Subject | Re: Nasty suprise with uptime |
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On Mon, Oct 29, 2001 at 03:20:02PM -0800, you [J Sloan] claimed: > Mike Fedyk wrote: > > > On Mon, Oct 29, 2001 at 12:31:12PM -0800, J Sloan wrote: > > > Say it ain't so! maybe I'm a bit dense, but is the 2.4 kernel also going > > > to wrap around after 497 days uptime? I'd be glad if someone would > > > point out the error in my understanding. > > > > Ahh, so that's why there haven't been any reports of higher uptimes... ;) > > Yes, it all makes sense now - > > Say, if the uptime field were unsigned it could > reach 995 days uptime before wraparound -
AFAIK, the jiffies field _is_ unsigned already. In fact 2.0 kernels had some problems at 2^31 HZ as well. (Stuff like select misbehaving, and some procps utils giving incorrect results).
2^32 HZ is 2^32/100 seconds is 2^32/3600/100/24 = 497.1 days. 2^31 HZ is 2^31/100 seconds is 2^31/3600/100/24 = 248.55 days.
(HZ=1/100 by default on x86 etc, it is 1/1024 or 1/1000 at least on alpha).
You need 64 bit jiffies for longer uptimes.
BTW, on win95 the HZ is 1024, which caused it to _always_ crash if it ever reached 48.5 days of uptime. I've seen NT4 SMP to to crash at same point as well (though it doesn't do it always).
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