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Date: Wed, 10 Mar 2010 09:19:30 -0800 From: john stultz <johnstul@...ibm.com> To: Srinivas Nayak <sinu_nayak2001@...oo.co.in> Cc: linux-kernel@...r.kernel.org Subject: Re: BUG: Is it a bug in Linux time() function or Linux OS calls? On Tue, Mar 9, 2010 at 11:59 PM, Srinivas Nayak <sinu_nayak2001@...oo.co.in> 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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