[lkml]   [2001]   [Apr]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: uninteruptable sleep (D state => load_avrg++)
    On Wed, 4 Apr 2001, christophe barbe wrote:

    > From me, a POV without technical reasons is not a philosical one
    > but more certainly an historical one.

    there may be (and indeed probably are) good technical reasons, however
    i am not well enough informed to say what they are.

    > Process that will be runnable are not participating to the load so
    > why incrementing the load average.

    As i understand it:

    load avg by nature is a measure of how many processes are 'runnable'
    (ie waiting to run) over time.

    a process waiting for the kernel to complete IO will indeed be
    runnable as soon as the kernel is finished.

    instead of waiting for CPU time (as with processes marked R), instead
    these processes are waiting for kernel to complete.

    > Moreover if a process should be
    > in state D only for a short time, the influence of the
    > incrementation should be near null for an AVERAGE value.

    because the number of processes asleep, waiting on kernel to complete
    IO may reasonably be considered to be a load.

    imagine a box with a bunch of processes that do almost nothing but
    call on the kernel to do IO. If you only count the runnable state
    towards load_avg then your load_avg will be very low, even though your
    box is swamped - you are ignoring the work of the kernel.

    if you count D towards load_avg then it will reflect this abstract
    'load' concept more accurately.

    Ie, counting D towards load_avg is a way of taking kernel IO work into
    account when calculating the load average figures.

    > What's the technical reason behind this load_avrg++ ???
    > Christophe


    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to
    More majordomo info at
    Please read the FAQ at

     \ /
      Last update: 2005-03-22 13:23    [W:0.023 / U:8.364 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site