Re: BUG: Is it a bug in Linux time() function or Linux OS calls?

[Srinivas Nayak]

Dear John,

Thanks for your answer. This is informative.

With best regards,
 
Yours sincerely,
Srinivas Nayak
 
My Home page: http://www.mathmeth.com/sn/
My Blog: http://srinivas-nayak.blogspot.com


--- On Wed, 10/3/10, john stultz <johnstul@xxxxxxxxxx> wrote:

> From: john stultz <johnstul@xxxxxxxxxx>
> Subject: Re: BUG: Is it a bug in Linux time() function or Linux OS calls?
> To: "Srinivas Nayak" <sinu_nayak2001@xxxxxxxxxxx>
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Date: Wednesday, 10 March, 2010, 10:49 PM
> On Tue, Mar 9, 2010 at 11:59 PM,
> Srinivas Nayak
> <sinu_nayak2001@xxxxxxxxxxx>
> wrote:
> > I wrote a small program, that creates files at an
> interval of 1 minute. But the time at which the file is
> created and last written and the last modification time of
> the file as shown by ls command differs by 1 second. The
> code and the output is presented below. please let me know
> where could be the bug?
> >
> [snip]
> > Some system info:
> > ===========
> > Linux new 2.6.24-19-server #1 SMP Wed Jun 18 14:44:47
> UTC 2008 x86_64 GNU/Linux
> > Gnu C                  4.2.4
> > Linux C Library        2.7
> > binutils               2.18.0.20080103
> > util-linux             2.13.1
> > Console-tools          0.2.3
> > Sh-utils               6.10
> > ===========
> 
> Hrm. Is CONFIG_NO_HZ enabled?  If so this is a known
> issue. The
> filesystem timestamps use xtime, which is normally updated
> every HZ.
> However to reduce overhead with NO_HZ we changed the update
> to be a
> half-second, which can cause issues like what you
> describe.
> 
> The issue has since been resolved, so I'd be interested to
> hear if you
> can still reproduce it on a more recent kernel.
> 
> thanks
> -john
> 


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