lkml.org 
[lkml]   [2004]   [Aug]   [31]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH] Re: boot time, process start time, and NOW time
    Tim Schmielau wrote:
    > On Mon, 30 Aug 2004, john stultz wrote:
    >
    >
    >>On Mon, 2004-08-30 at 16:00, Tim Schmielau wrote:
    >>
    >>>George, please excuse my lack of understanding. What again where the
    >>>precise reasons to have an ntp-corrected uptime?
    >>
    >>Ah, here's the thread with the first mention of it that I could find.
    >>
    >>http://www.uwsg.iu.edu/hypermail/linux/kernel/0306.1/1471.html

    As I recall the problem was that jiffies since boot was being converted to get
    uptime base on 1/HZ = 1 jiffie. Since it is really not quite that, there was an
    error. Using clock_monotonic seemed like the right answer as it eliminated the
    error AND made the result consistant with get_clock(CLOCK_MONOTONIC,..).

    The alternate answer is, of course, to directly convert the elapsed jiffies.
    The main problem with this is that this can be a BIG number and, therefor, the
    math needs to be carefully. And, of course, it is inconsistant with
    get_clock(), but that is a new interface...

    George
    >
    >
    > Ah, it seems George indeed did the patch because of these problems:
    >
    > http://www.uwsg.iu.edu/hypermail/linux/kernel/0306.1/1641.html
    >
    > However, the actual reason were just missing wall_to_monotonic
    > initializations:
    >
    > http://www.uwsg.iu.edu/hypermail/linux/kernel/0306.2/1330.html
    >
    > This was fixed in mainline:
    >
    > http://linus.bkbits.net:8080/linux-2.5/cset%403f0e60dcpIosK3b5_uJ-aD9Mare17w
    >
    > Tim
    >

    --
    George Anzinger george@mvista.com
    High-res-timers: http://sourceforge.net/projects/high-res-timers/
    Preemption patch: http://www.kernel.org/pub/linux/kernel/people/rml

    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2005-03-22 14:05    [W:0.049 / U:30.956 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site