Can jiffies freeze?

anish singh anish198519851985 at
Tue Jan 22 02:33:08 EST 2013

On Tue, Jan 22, 2013 at 11:21 AM, sandeep kumar
<coolsandyforyou at> wrote:
> Hi all
> As far as I know jiffie counter is incremented HZ times/second. And it is
> used to measure the time lapses in the kernel code.
> I m seeing a case where, actualy time spent in some module using giffies is
> zero, but while seeing UART logs i am seein 2 sec time difference. I dont
Please post the code here regarding how did you find out it is zero.
> know how to interpret this. The case which i am seeing, hrtimers are not
> enabled yet, so only thing i can rely are on jiffies.
> My question here is,
> Is it possible that the measured time lapse shown is "0"(jiffie count is
> same before and after), but actually some time is spent?(say some 2 sec)
> In another way..can jiffies may freeze for some time?
Is your watchdog enabled?If it is then you will see panic happening
i.e. soft lockup.
> Please clarify...
> --
> With regards,
> Sandeep Kumar Anantapalli,
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