what will happen when the jiffies overflow ?

Gaurav Jain gjainroorkee at gmail.com
Thu Sep 20 11:13:53 EDT 2012


Btw, jiffies is now stored as a 64 bit variable internally in the kernel
(not 32 bit), although to maintain compatibility with the older code, it
can be still 'treated' as a 32-bit variable. In reality, overflow would
take a lot more time than 497 days, but if you read only the first 32 bits,
then you are right about the 497 day thing.

~Gaurav

On Thu, Sep 20, 2012 at 8:30 PM, Dave Hylands <dhylands at gmail.com> wrote:

> Hi,
>
> On Thu, Sep 20, 2012 at 7:09 AM, Fan Yang <lljyangfan at gmail.com> wrote:
> > hi all:
> >        As far as I known, the var jiffies in the kernel will overflow
> after
> > 497days as the Hz defined 100. So what waill happen when the jiffies
> > overflow?
>
> It will start back at zero.
>
> Everything should continue to work as before.
>
> In fact, jiffies are initialized to -300 seconds, so that it will
> overflow 5 minutes after startup, just to verify that everything works
> properly.
>
> --
> Dave Hylands
> Shuswap, BC, Canada
> http://www.davehylands.com
>
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>



-- 
Gaurav Jain
Associate Software Engineer
VxVM Escalations Team, SAMG
Symantec Software India Pvt. Ltd.
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