• Nathan Lynch's avatar
    sched: do not count frozen tasks toward load · e3c8ca83
    Nathan Lynch authored
    Freezing tasks via the cgroup freezer causes the load average to climb
    because the freezer's current implementation puts frozen tasks in
    uninterruptible sleep (D state).
    Some applications which perform job-scheduling functions consult the
    load average when making decisions.  If a cgroup is frozen, the load
    average does not provide a useful measure of the system's utilization
    to such applications.  This is especially inconvenient if the job
    scheduler employs the cgroup freezer as a mechanism for preempting low
    priority jobs.  Contrast this with using SIGSTOP for the same purpose:
    the stopped tasks do not count toward system load.
    Change task_contributes_to_load() to return false if the task is
    frozen.  This results in /proc/loadavg behavior that better meets
    users' expectations.
    Signed-off-by: default avatarNathan Lynch <ntl@pobox.com>
    Acked-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Acked-by: default avatarNigel Cunningham <nigel@tuxonice.net>
    Tested-by: default avatarNigel Cunningham <nigel@tuxonice.net>
    Cc: <stable@kernel.org>
    Cc: containers@lists.linux-foundation.org
    Cc: linux-pm@lists.linux-foundation.org
    Cc: Matt Helsley <matthltc@us.ibm.com>
    LKML-Reference: <20090408194512.47a99b95@manatee.lan>
    Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
sched.h 69.4 KB