[PATCH v2 1/2] sched/debug: show task state on /proc/sched_debug

[Xie XiuQi]

Currently, we print the runnable task in /proc/sched_debug, but there is no task state information.
We don't know which task is in runqueue, and which task is in sleep. For the convenience of debugging,
in this patch, we add task state in runnable task list, like this:

  runnable tasks:
   S           task   PID         tree-key  switches  prio     wait-time             sum-exec        sum-sleep
  -----------------------------------------------------------------------------------------------------------
   S   watchdog/239  1452       -11.917445      2811     0         0.000000         8.949306         0.000000 7 0 /
   S  migration/239  1453     20686.367740         8     0         0.000000     16215.720897         0.000000 7 0 /
   S  ksoftirqd/239  1454    115383.841071        12   120         0.000000         0.200683         0.000000 7 0 /
  >R           test 21287      4872.190970       407   120         0.000000      4874.911790         0.000000 7 0 /autogroup-150
   R           test 21288      4868.385454       401   120         0.000000      3672.341489         0.000000 7 0 /autogroup-150
   R           test 21289      4868.326776       384   120         0.000000      3424.934159         0.000000 7 0 /autogroup-150

Signed-off-by: Xie XiuQi <xiexiuqi@xxxxxxxxxx>
---
 kernel/sched/debug.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index 38f0193..60f7e20 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -421,13 +421,19 @@ static char *task_group_path(struct task_group *tg)
 }
 #endif
 
+static const char stat_nam[] = TASK_STATE_TO_CHAR_STR;
+
 static void
 print_task(struct seq_file *m, struct rq *rq, struct task_struct *p)
 {
-	if (rq->curr == p)
-		SEQ_printf(m, "R");
-	else
-		SEQ_printf(m, " ");
+	unsigned long state;
+
+	if (rq->curr == p) {
+		SEQ_printf(m, ">R");
+	} else {
+		state = p->state ? __ffs(p->state) + 1 : 0;
+		SEQ_printf(m, " %c", state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?');
+	}
 
 	SEQ_printf(m, "%15s %5d %9Ld.%06ld %9Ld %5d ",
 		p->comm, task_pid_nr(p),
@@ -456,9 +462,9 @@ static void print_rq(struct seq_file *m, struct rq *rq, int rq_cpu)
 
 	SEQ_printf(m,
 	"\nrunnable tasks:\n"
-	"            task   PID         tree-key  switches  prio"
+	" S           task   PID         tree-key  switches  prio"
 	"     wait-time             sum-exec        sum-sleep\n"
-	"------------------------------------------------------"
+	"-------------------------------------------------------"
 	"----------------------------------------------------\n");
 
 	rcu_read_lock();
-- 
1.8.3.1