Re: time_second vs. time_uptime

From: Jung-uk Kim (jkim_at_FreeBSD.org)
Date: 09/10/05

  • Next message: Poul-Henning Kamp: "Re: time_second vs. time_uptime" 
    To: Brooks Davis <brooks@one-eyed-alien.net>
Date: Fri, 9 Sep 2005 18:35:50 -0400

    On Friday 09 September 2005 05:48 pm, Brooks Davis wrote:
    > On Fri, Sep 09, 2005 at 05:44:24PM -0400, Jung-uk Kim wrote:
    > > If I read the source correctly, time_second can go backwards or
    > > forwards when there is a leap second but time_uptime cannot. Am
    > > I right? If my assumption is right, it seems we have some
    > > misuses in kernel, e. g., sched_sync() in sys/kern/vfs_subr.c.
    > > It may not be critical but it worries me a little because a leap
    > > second is scheduled to occur at the end of this year. ;-)
    >
    > Yes, uptime increases monotonically, but leap seconds and
    > adjustments such as those made by ntpdate will make simple time
    > values jump around. This bit me when I first did the interface
    > epochs since absolute times are not necessarily unique.

    It seems the most commonly misused places are networks stacks. It's
    understandable because time_uptime is relatively new. :-)

    http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/kern/kern_tc.c.diff?r1=1.140&r2=1.141

    Anyway let's start fixing!

    Thanks,

    Jung-uk Kim

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