ANDROID: sched/tune: add sysctl interface to define a boost value

The current (CFS) scheduler implementation does not allow "to boost"
tasks performance by running them at a higher OPP compared to the
minimum required to meet their workload demands.

To support tasks performance boosting the scheduler should provide a
"knob" which allows to tune how much the system is going to be optimised
for energy efficiency vs performance.

This patch is the first of a series which provides a simple interface to
define a tuning knob. One system-wide "boost" tunable is exposed via:
  /proc/sys/kernel/sched_cfs_boost
which can be configured in the range [0..100], to define a percentage
where:
  - 0%   boost requires to operate in "standard" mode by scheduling
         tasks at the minimum capacities required by the workload demand
  - 100% boost requires to push at maximum the task performances,
         "regardless" of the incurred energy consumption

A boost value in between these two boundaries is used to bias the
power/performance trade-off, the higher the boost value the more the
scheduler is biased toward performance boosting instead of energy
efficiency.

cc: Ingo Molnar <mingo@redhat.com>
cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Andres Oportus <andresoportus@google.com>

Bug: 62598057
Change-Id: I33c5e5a3406dddee2005786f4d97c56334c4662b
(cherry picked from commit 69fa4c768a73c25b9b3f26d074295c53f839a57c)

1 files changed, 16 insertions, 0 deletions

diff --git a/kernel/sched/tune.c b/kernel/sched/tune.c
new file mode 100644
index 000000000000..a93af9c2f267
--- /dev/null
+++ b/kernel/sched/tune.c
@@ -0,0 +1,16 @@
+#include "sched.h"
+
+unsigned int sysctl_sched_cfs_boost __read_mostly;
+
+int
+sysctl_sched_cfs_boost_handler(struct ctl_table *table, int write,
+			       void __user *buffer, size_t *lenp,
+			       loff_t *ppos)
+{
+	int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
+
+	if (ret || !write)
+		return ret;
+
+	return 0;
+}