[RFC PATCH 2/3] psi: cgroup v1 support

[Joseph Qi <joseph.qi@linux.alibaba.com>]

Implements pressure stall tracking for cgroup v1.

Signed-off-by: Joseph Qi <joseph.qi@linux.alibaba.com>
---
 kernel/sched/psi.c | 65 +++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 56 insertions(+), 9 deletions(-)

diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
index 7acc632c3b82..909083c828d5 100644
--- a/kernel/sched/psi.c
+++ b/kernel/sched/psi.c
@@ -719,13 +719,30 @@ static u32 psi_group_change(struct psi_group *group, int cpu,
 	return state_mask;
 }
 
-static struct psi_group *iterate_groups(struct task_struct *task, void **iter)
+static struct cgroup *psi_task_cgroup(struct task_struct *task, enum psi_res res)
+{
+	switch (res) {
+	case NR_PSI_RESOURCES:
+		return task_dfl_cgroup(task);
+	case PSI_IO:
+		return task_cgroup(task, io_cgrp_subsys.id);
+	case PSI_MEM:
+		return task_cgroup(task, memory_cgrp_subsys.id);
+	case PSI_CPU:
+		return task_cgroup(task, cpu_cgrp_subsys.id);
+	default:  /* won't reach here */
+		return NULL;
+	}
+}
+
+static struct psi_group *iterate_groups(struct task_struct *task, void **iter,
+					enum psi_res res)
 {
 #ifdef CONFIG_CGROUPS
 	struct cgroup *cgroup = NULL;
 
 	if (!*iter)
-		cgroup = task->cgroups->dfl_cgrp;
+		cgroup = psi_task_cgroup(task, res);
 	else if (*iter == &psi_system)
 		return NULL;
 	else
@@ -776,15 +793,45 @@ void psi_task_change(struct task_struct *task, int clear, int set)
 		     wq_worker_last_func(task) == psi_avgs_work))
 		wake_clock = false;
 
-	while ((group = iterate_groups(task, &iter))) {
-		u32 state_mask = psi_group_change(group, cpu, clear, set);
+	if (cgroup_subsys_on_dfl(cpu_cgrp_subsys) ||
+	    cgroup_subsys_on_dfl(memory_cgrp_subsys) ||
+	    cgroup_subsys_on_dfl(io_cgrp_subsys)) {
+		while ((group = iterate_groups(task, &iter, NR_PSI_RESOURCES))) {
+			u32 state_mask = psi_group_change(group, cpu, clear, set);
 
-		if (state_mask & group->poll_states)
-			psi_schedule_poll_work(group, 1);
+			if (state_mask & group->poll_states)
+				psi_schedule_poll_work(group, 1);
 
-		if (wake_clock && !delayed_work_pending(&group->avgs_work))
-			schedule_delayed_work(&group->avgs_work, PSI_FREQ);
+			if (wake_clock && !delayed_work_pending(&group->avgs_work))
+				schedule_delayed_work(&group->avgs_work, PSI_FREQ);
+		}
+	} else {
+		enum psi_task_count i;
+		enum psi_res res;
+		int psi_flags = clear | set;
+
+		for (i = NR_IOWAIT; i < NR_PSI_TASK_COUNTS; i++) {
+			if ((i == NR_IOWAIT) && (psi_flags & TSK_IOWAIT))
+				res = PSI_IO;
+			else if ((i == NR_MEMSTALL) && (psi_flags & TSK_MEMSTALL))
+				res = PSI_MEM;
+			else if ((i == NR_RUNNING) && (psi_flags & TSK_RUNNING))
+				res = PSI_CPU;
+			else
+				continue;
+
+			while ((group = iterate_groups(task, &iter, res))) {
+				u32 state_mask = psi_group_change(group, cpu, clear, set);
+
+				if (state_mask & group->poll_states)
+					psi_schedule_poll_work(group, 1);
+
+				if (wake_clock && !delayed_work_pending(&group->avgs_work))
+					schedule_delayed_work(&group->avgs_work, PSI_FREQ);
+			}
+		}
 	}
+
 }
 
 void psi_memstall_tick(struct task_struct *task, int cpu)
@@ -792,7 +839,7 @@ void psi_memstall_tick(struct task_struct *task, int cpu)
 	struct psi_group *group;
 	void *iter = NULL;
 
-	while ((group = iterate_groups(task, &iter))) {
+	while ((group = iterate_groups(task, &iter, PSI_MEM))) {
 		struct psi_group_cpu *groupc;
 
 		groupc = per_cpu_ptr(group->pcpu, cpu);
-- 
2.19.1.856.g8858448bb