lkml.org 
[lkml]   [2010]   [May]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [RFC] oom-kill: give the dying task a higher priority
    On Fri, May 28, 2010 at 09:53:05AM -0300, Luis Claudio R. Goncalves wrote:
    > On Fri, May 28, 2010 at 02:59:02PM +0900, KOSAKI Motohiro wrote:
    > | > RT Task
    > | >
    > | > void non-RT-function()
    > | > {
    > | > system call();
    > | > buffer = malloc();
    > | > memset(buffer);
    > | > }
    > | > /*
    > | > * We make sure this function must be executed in some millisecond
    > | > */
    > | > void RT-function()
    > | > {
    > | > some calculation(); <- This doesn't have no dynamic characteristic
    > | > }
    > | > int main()
    > | > {
    > | > non-RT-function();
    > | > /* This function make sure RT-function cannot preempt by others */
    > | > set_RT_max_high_priority();
    > | > RT-function A();
    > | > set_normal_priority();
    > | > non-RT-function();
    > | > }
    > | >
    > | > We don't want realtime in whole function of the task. What we want is
    > | > just RT-function A.
    > | > Of course, current Linux cannot make perfectly sure RT-functionA can
    > | > not preempt by others.
    > | > That's because some interrupt or exception happen. But RT-function A
    > | > doesn't related to any dynamic characteristic. What can justify to
    > | > preempt RT-function A by other processes?
    > |
    > | As far as my observation, RT-function always have some syscall. because pure
    > | calculation doesn't need deterministic guarantee. But _if_ you are really
    > | using such priority design. I'm ok maximum NonRT priority instead maximum
    > | RT priority too.
    >
    > I confess I failed to distinguish memcg OOM and system OOM and used "in
    > case of OOM kill the selected task the faster you can" as the guideline.
    > If the exit code path is short that shouldn't be a problem.
    >
    > Maybe the right way to go would be giving the dying task the biggest
    > priority inside that memcg to be sure that it will be the next process from
    > that memcg to be scheduled. Would that be reasonable?

    Hmm. I can't understand your point.
    What do you mean failing distinguish memcg and system OOM?

    We already have been distinguish it by mem_cgroup_out_of_memory.
    (but we have to enable CONFIG_CGROUP_MEM_RES_CTLR).
    So task selected in select_bad_process is one out of memcg's tasks when
    memcg have a memory pressure.

    Isn't it enough?
    --
    Kind regards,
    Minchan Kim


    \
     
     \ /
      Last update: 2010-05-28 16:09    [W:0.026 / U:30.204 seconds]
    ©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site