lkml.org 
[lkml]   [2008]   [Mar]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    SubjectRe: [BUG 2.6.25-rc3] scheduler/hotplug: some processes are dealocked when cpu is set to offline
    On Fri, 7 Mar 2008 14:02:20 +0100
    "Dmitry Adamushko" <dmitry.adamushko@gmail.com> wrote:

    > Hi,
    >
    > 'watchdog' is of SCHED_FIFO class. The standard load-balancer doesn't
    > move RT tasks between cpus anymore and there is a special mechanism in
    > scher_rt.c instead (I think, it's .25 material).
    >
    > So I wonder, whether __migrate_task() is still capable of properly
    > moving a RT task to another CPU (e.g. for the case when it's in
    > TASK_RUNNING state) without breaking something in the rt migration
    > mechanism (or whatever else) that would leave us with a runqueue in
    > the 'inconsistent' state...
    > (I've taken a quick look at the relevant code so can't confirm it yet)
    >
    > maybe it'd be faster if somebody could do a quick test now with the
    > following line commented out in kernel/softlockup.c :: watchdog()
    >
    > - sched_setscheduler(current, SCHED_FIFO, &param);
    >

    Yup, thanks. This:


    kernel/softirq.c | 2 +-
    kernel/softlockup.c | 2 +-
    kernel/stop_machine.c | 2 +-
    3 files changed, 3 insertions(+), 3 deletions(-)

    diff -puN kernel/softlockup.c~a kernel/softlockup.c
    --- a/kernel/softlockup.c~a
    +++ a/kernel/softlockup.c
    @@ -211,7 +211,7 @@ static int watchdog(void *__bind_cpu)
    struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
    int this_cpu = (long)__bind_cpu;

    - sched_setscheduler(current, SCHED_FIFO, &param);
    +// sched_setscheduler(current, SCHED_FIFO, &param);

    /* initialize timestamp */
    touch_softlockup_watchdog();
    diff -puN kernel/stop_machine.c~a kernel/stop_machine.c
    --- a/kernel/stop_machine.c~a
    +++ a/kernel/stop_machine.c
    @@ -188,7 +188,7 @@ struct task_struct *__stop_machine_run(i
    struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };

    /* One high-prio thread per cpu. We'll do this one. */
    - sched_setscheduler(p, SCHED_FIFO, &param);
    +// sched_setscheduler(p, SCHED_FIFO, &param);
    kthread_bind(p, cpu);
    wake_up_process(p);
    wait_for_completion(&smdata.done);
    diff -puN kernel/softirq.c~a kernel/softirq.c
    --- a/kernel/softirq.c~a
    +++ a/kernel/softirq.c
    @@ -622,7 +622,7 @@ static int __cpuinit cpu_callback(struct

    p = per_cpu(ksoftirqd, hotcpu);
    per_cpu(ksoftirqd, hotcpu) = NULL;
    - sched_setscheduler(p, SCHED_FIFO, &param);
    +// sched_setscheduler(p, SCHED_FIFO, &param);
    kthread_stop(p);
    takeover_tasklets(hotcpu);
    break;
    _
    fixes the wont-power-off regression.

    But 2.6.24 runs the watchdog threads SCHED_FIFO too. Are you saying that
    it's the migration code which changed?


    \
     
     \ /
      Last update: 2008-03-07 21:21    [W:0.024 / U:1.172 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site