psi: fix aggregation idle shut-off

[sfrench/cifs-2.6.git] / kernel / sched / psi.c

diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
index fe24de3fbc93805f0c1e913a85657a15d141ad2f..c3484785b17958df85b11ca2823a1f4a4d41f59b 100644 (file)
--- a/kernel/sched/psi.c
+++ b/kernel/sched/psi.c
@@ -124,6 +124,7 @@
  * sampling of the aggregate task states would be.
  */
 
+#include "../workqueue_internal.h"
 #include <linux/sched/loadavg.h>
 #include <linux/seq_file.h>
 #include <linux/proc_fs.h>
@@ -480,9 +481,6 @@ static void psi_group_change(struct psi_group *group, int cpu,
                        groupc->tasks[t]++;
 
        write_seqcount_end(&groupc->seq);
-
-       if (!delayed_work_pending(&group->clock_work))
-               schedule_delayed_work(&group->clock_work, PSI_FREQ);
 }
 
 static struct psi_group *iterate_groups(struct task_struct *task, void **iter)
@@ -513,6 +511,7 @@ void psi_task_change(struct task_struct *task, int clear, int set)
 {
        int cpu = task_cpu(task);
        struct psi_group *group;
+       bool wake_clock = true;
        void *iter = NULL;
 
        if (!task->pid)
@@ -530,8 +529,22 @@ void psi_task_change(struct task_struct *task, int clear, int set)
        task->psi_flags &= ~clear;
        task->psi_flags |= set;
 
-       while ((group = iterate_groups(task, &iter)))
+       /*
+        * Periodic aggregation shuts off if there is a period of no
+        * task changes, so we wake it back up if necessary. However,
+        * don't do this if the task change is the aggregation worker
+        * itself going to sleep, or we'll ping-pong forever.
+        */
+       if (unlikely((clear & TSK_RUNNING) &&
+                    (task->flags & PF_WQ_WORKER) &&
+                    wq_worker_last_func(task) == psi_update_work))
+               wake_clock = false;
+
+       while ((group = iterate_groups(task, &iter))) {
                psi_group_change(group, cpu, clear, set);
+               if (wake_clock && !delayed_work_pending(&group->clock_work))
+                       schedule_delayed_work(&group->clock_work, PSI_FREQ);
+       }
 }
 
 void psi_memstall_tick(struct task_struct *task, int cpu)