lkml.org 
[lkml]   [2015]   [Apr]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH v7 3/3] procfs: treat parked tasks as sleeping for task state
    Date
    Allowing watchdog threads to be parked means that we now have the
    opportunity of actually seeing persistent parked threads in the output
    of /proc's stat and status files. The existing code reported such
    threads as "Running", which is kind-of true if you think of the case
    where we park them as part of taking cpus offline. But if we allow
    parking them indefinitely, "Running" is pretty misleading, so we report
    them as "Sleeping" instead.

    We could simply report them with a new string, "Parked", but it feels
    like it's a bit risky for userspace to see unexpected new values.
    The scheduler does report parked tasks with a "P" in debugging output
    from sched_show_task() or dump_cpu_task(), but that's a different API.

    This change seemed slightly cleaner than updating the task_state_array
    to have additional rows. TASK_DEAD should be subsumed by the exit_state
    bits; TASK_WAKEKILL is just a modifier; and TASK_WAKING can very
    reasonably be reported as "Running" (as it is now). Only TASK_PARKED
    shows up with unreasonable output here.

    Signed-off-by: Chris Metcalf <cmetcalf@ezchip.com>
    ---
    fs/proc/array.c | 4 ++++
    1 file changed, 4 insertions(+)

    diff --git a/fs/proc/array.c b/fs/proc/array.c
    index a3893b7505b2..2eb623ffb0b7 100644
    --- a/fs/proc/array.c
    +++ b/fs/proc/array.c
    @@ -126,6 +126,10 @@ static inline const char *get_task_state(struct task_struct *tsk)
    {
    unsigned int state = (tsk->state | tsk->exit_state) & TASK_REPORT;

    + /* Treat parked tasks as sleeping. */
    + if (state == TASK_PARKED)
    + state = TASK_SLEEPING;
    +
    BUILD_BUG_ON(1 + ilog2(TASK_REPORT) != ARRAY_SIZE(task_state_array)-1);

    return task_state_array[fls(state)];
    --
    2.1.2


    \
     
     \ /
      Last update: 2015-04-10 23:21    [W:2.856 / U:0.420 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site