From a0b0997b5cd674c4d5e77bafb9f6499c8c9bf04e Mon Sep 17 00:00:00 2001
From: derMihai <mihairenea@gmail.com>
Date: Mon, 25 Mar 2019 18:22:31 +0100
Subject: [PATCH] determine_next_mode(): check if process is runnable
---
kernel/sched/sched.h | 26 ++++++++++++++++++++++++--
1 file changed, 24 insertions(+), 2 deletions(-)
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index eec6da7a2bf5..1e2a79da89d8 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -904,8 +904,30 @@ static inline int determine_next_mode_pb(struct rq *rq)
* Is the tick interrupt active in this moment?
*/
if(pb->count_admin_cycles > pb->n_admin_cycles){
- mode = PB_EXEC_MODE;
- pb->count_admin_cycles = 0;
+ /*
+ * If the current plan_entry's process is blocked, we cannot
+ * go in PB_EXEC_MODE. The reason could be, that administrative
+ * tasks were pushed forward by the default scheduler and the IO
+ * starved. We have to wait until the process is runnable.
+ */
+ if (pb->plan[pb->c_entry].task_struct->state >= 0) {
+ /*
+ * 0 == Runnable (IO succeeded)
+ * >0 == stopped (Process finished)
+ */
+ mode = PB_EXEC_MODE;
+ pb->count_admin_cycles = 0;
+
+ } else {
+ /*
+ * -1 == unrunnable
+ */
+ mode = PB_ADMIN_MODE;
+ printk(KERN_WARNING "PB TASK %llu BLOCKED BY IO FOR %llu TOO MANY TICKS\n",
+ pb->plan[pb->c_entry].task_id,
+ pb->count_admin_cycles - pb->n_admin_cycles);
+ }
+
}else{
mode = PB_ADMIN_MODE;
}
--
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