commit 489646b879ede582b6b00803edd3f777aede4d85
author YT Chang <yt.chang@mediatek.com> Thu Sep 03 16:04:01 2020 +0800
committer Todd Kjos <tkjos@google.com> Tue Oct 06 20:22:51 2020 +0000
tree a1bf55cba9a520bc6f9c54b8adff754908896726
parent ab402fc4c18734e05b6419b93077dd37f6687ed4

ANDROID: sched: add restrict vendor hook to modify load balance behavior

For modifying load balance policy, we add the hook on
find_busiest_group().
It allows us to modify load balance paths.

Bug: 168248326
Signed-off-by: YT Chang <yt.chang@mediatek.com>
Change-Id: I77ec043576139806551b978eb1bdf9f637442dfb
(cherry picked from commit a2ca8408de6183364b4c17f341f06e875bc7a1c1)

drivers/android/vendor_hooks.c

diff --git a/drivers/android/vendor_hooks.c b/drivers/android/vendor_hooks.c
index ee31dde..88dea192 100644
--- a/drivers/android/vendor_hooks.c
+++ b/drivers/android/vendor_hooks.c
@@ -55,3 +55,4 @@
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_alter_futex_plist_add);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_ipi_stop);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_wq_lockup_pool);
+EXPORT_TRACEPOINT_SYMBOL_GPL(android_rvh_find_busiest_group);

include/trace/hooks/sched.h

diff --git a/include/trace/hooks/sched.h b/include/trace/hooks/sched.h
index 6ac7dd6..4e2be4d 100644
--- a/include/trace/hooks/sched.h
+++ b/include/trace/hooks/sched.h
@@ -65,6 +65,11 @@
 DECLARE_RESTRICTED_HOOK(android_rvh_setscheduler,
 	TP_PROTO(struct task_struct *p),
 	TP_ARGS(p), 1);
+
+struct sched_group;
+DECLARE_RESTRICTED_HOOK(android_rvh_find_busiest_group,
+	TP_PROTO(struct sched_group *busiest, struct rq *dst_rq, int *out_balance),
+		TP_ARGS(busiest, dst_rq, out_balance), 1);
 #else
 #define trace_android_rvh_select_task_rq_fair(p, prev_cpu, sd_flag, wake_flags, new_cpu)
 #define trace_android_rvh_select_task_rq_rt(p, prev_cpu, sd_flag, wake_flags, new_cpu)
@@ -79,6 +84,7 @@
 #define trace_android_rvh_rtmutex_prepare_setprio(p, pi_task)
 #define trace_android_rvh_set_user_nice(p, nice)
 #define trace_android_rvh_setscheduler(p)
+#define trace_android_rvh_find_busiest_group(busiest, dst_rq, out_balance)
 #endif
 #endif /* _TRACE_HOOK_SCHED_H */
 /* This part must be outside protection */

kernel/sched/fair.c

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 62aab41..fdca85b 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -8738,8 +8738,12 @@
 
 	if (sched_energy_enabled()) {
 		struct root_domain *rd = env->dst_rq->rd;
+		int out_balance = 1;
 
-		if (rcu_dereference(rd->pd) && !READ_ONCE(rd->overutilized))
+		trace_android_rvh_find_busiest_group(sds.busiest, env->dst_rq,
+					&out_balance);
+		if (rcu_dereference(rd->pd) && !READ_ONCE(rd->overutilized)
+					&& out_balance)
 			goto out_balanced;
 	}