> > I have got an increasingly annoying problem with our fairly new (fall
> > '02) Dual Athlon2k+ Gigabyte 7dpxdw linux system running 2.4.20.
> I am using the exact same kernel (a lot of folks are). There
> is no such jumping on my system.
> Try this program:
[... prg1.c ...]
> If this shows time jumping around you have one of either:
>
> (1) Bad timer channel 0 chip (PIT).
> (2) Some daemon trying to sync time with another system.
> (3) You are traveling too close to the speed of light.
It just exits immediately with exit code 1. (*shrug*)
> Now, your script shows time in fractional seconds.
>
> > 1048608745.61 > 1048608745.60
>
> You can modify the program to do this:
[... prg2.c ...]
> There should be no jumping around -- and there isn't on
> any system I've tested this on.
When I run this code it begins to put out Prev N New M lines.
Prev 1048615862810879.000000 New 1048615862759879.000000
Prev 1048615862870879.000000 New 1048615862819878.000000
Prev 1048615862900879.000000 New 1048615862849902.000000
Prev 1048615862960882.000000 New 1048615862909875.000000
[-------- cut --------]
After a few seconds of run time random processes on my machine begin to
crash, or I get kernel oopses and kernel freezes. Looks very much like
heavy use of gettimeofday() causes random writes in system memory.
> > Software crashes are regularly - naturally. No programmer expects system
> > timers going back in time.
> Hmmm, software should never crash. Even if the timers jump backwards
> as you say, they should eventually time-out. If you have crashes, this
> may point to other hardware problems as well.
E.g. which type of hardware problem?
Thanks a million for your help so far, it is great to experience how
fast people are respoding!
I'll evaluate that other suggestion about TSC_DISABLE now and will get
back to you as soon as I can tell you more.
Kind regards,
F. Behrens
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