lkml.org 
[lkml]   [2008]   [Jul]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    SubjectRe: + pm-introduce-new-interfaces-schedule_work_on-and-queue_work_on.patch added to -mm tree
    (Gautham cc'ed)

    On 07/11, Andrew Morton wrote:
    >
    > Subject: pm: introduce new interfaces schedule_work_on() and queue_work_on()
    > From: Zhang Rui <rui.zhang@intel.com>
    >
    > This interface allows adding a job on a specific cpu.
    >
    > Although a work struct on a cpu will be scheduled to other cpu if the cpu
    > dies, there is a recursion if a work task tries to offline the cpu it's
    > running on. we need to schedule the task to a specific cpu in this case.
    > http://bugzilla.kernel.org/show_bug.cgi?id=10897

    So, this is used in http://bugzilla.kernel.org/attachment.cgi?id=16707

    --- linux-2.6.orig/kernel/power/poweroff.c 2008-06-30 16:01:35.000000000 +0800
    +++ linux-2.6/kernel/power/poweroff.c 2008-07-03 10:50:05.000000000 +0800
    @@ -25,7 +25,8 @@

    static void handle_poweroff(int key, struct tty_struct *tty)
    {
    - schedule_work(&poweroff_work);
    + /* run sysrq poweroff on boot cpu */
    + schedule_work_on(first_cpu(cpu_online_map), &poweroff_work);
    }

    static struct sysrq_key_op sysrq_poweroff_op = {

    A couple of silly questions, I don't understand the low-level details.

    This patch (and kernel_power_off() afaics) assumes that the boot cpu
    can't be cpu_down()'ed. Is it true in general? For example, grep shows
    that arch/s390/kernel/smp.c:topology_init()->smp_add_present_cpu()
    sets ->hotpluggable = 1 for all present CPUs?

    Another question. I can't understand why first_cpu(cpu_online_map) is
    always the boot CPU on every arch. IOW, shouldn't boot_cpu_init() set
    some "boot_cpu = smp_processor_id()" which should be use instead of
    first_cpu(cpu_online_map) ?

    Thanks,

    Oleg.


    \
     
     \ /
      Last update: 2008-07-12 18:21    [W:3.549 / U:0.788 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site