lkml.org 
[lkml]   [2015]   [Apr]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v9 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>
---
v9: fix to check tsk->state, and to set to TASK_INTERRUPTIBLE

fs/proc/array.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/fs/proc/array.c b/fs/proc/array.c
index a3893b7505b2..2a59d061941e 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 (tsk->state == TASK_PARKED)
+ state = TASK_INTERRUPTIBLE;
+
BUILD_BUG_ON(1 + ilog2(TASK_REPORT) != ARRAY_SIZE(task_state_array)-1);

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


\
 
 \ /
  Last update: 2015-04-17 21:01    [W:0.258 / U:3.316 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site