[RFC PATCH v1 14/18] sched: add new fields to task_struct

[Stefan Roesch <shr@fb.com>]

Add two new fields to the task_struct to support async
write throttling.

  - One field to store how long writes are throttled: bdp_pause
  - The other field to store the number of dirtied pages:
    bdp_nr_dirtied_pause

Signed-off-by: Stefan Roesch <shr@fb.com>
---
 include/linux/sched.h | 3 +++
 kernel/fork.c         | 1 +
 2 files changed, 4 insertions(+)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index a8911b1f35aa..98d70f2945e3 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1327,6 +1327,9 @@ struct task_struct {
 	/* Start of a write-and-pause period: */
 	unsigned long			dirty_paused_when;
 
+	unsigned long			bdp_pause;
+	int				bdp_nr_dirtied_pause;
+
 #ifdef CONFIG_LATENCYTOP
 	int				latency_record_count;
 	struct latency_record		latency_record[LT_SAVECOUNT];
diff --git a/kernel/fork.c b/kernel/fork.c
index 9796897560ab..5bc6298827fc 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2316,6 +2316,7 @@ static __latent_entropy struct task_struct *copy_process(
 	p->nr_dirtied = 0;
 	p->nr_dirtied_pause = 128 >> (PAGE_SHIFT - 10);
 	p->dirty_paused_when = 0;
+	p->bdp_nr_dirtied_pause = -1;
 
 	p->pdeath_signal = 0;
 	INIT_LIST_HEAD(&p->thread_group);
-- 
2.30.2