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SubjectJiffies Wraparound (was Re: interrupt counts) (fwd)
Date
Forwarded message:
> From: mlord <mlord@pobox.com>
> Newsgroups: linux.dev.kernel
> Subject: Jiffies Wraparound (was Re: interrupt counts)
> Date: Mon, 19 Aug 1996 21:57:35 -0400

> Jon Lewis wrote:
> >
> > Just out of curiosity, what's going to happen in about 2 months when my
> > irq 11 counter hits 4294967296? Will it happily wrap, or are things
> > likely to get upset?
>
> The one that really worries me is having the "jiffies" wrap around,
> an event which will happen every 17 months or so on production systems.
>
> A *lot* of the kernel will malfunction when that happens.

Its not supposed to break anything, but I doubt it has ever been tested.
Something that might be interesting is to compile a kernel with the counter
pre-initialized so that it will overflow in about 5 minutes. Then some
network connections, compilers, etc. could be started up, and we could
see what happened when it overflowed.

Jim

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