commit 578db5dbecfa7343a5e0260a397ccafc0a14eba6
author Joonwoo Park <joonwoop@codeaurora.org> Thu Jun 01 10:59:12 2017 -0700
committer Andres Oportus <andresoportus@google.com> Thu Aug 03 15:30:42 2017 -0700
tree 6e7a4dd7424822563dc99b6081cc5ee9ddbc245e
parent 54a8edbf1d319c67e61304c714a4826e314a1034

ANDROID: sched: walt: fix window misalignment when HZ=300

Due to rounding error hrtimer tick interval becomes 3333333 ns when HZ=300.
Consequently the tick time stamp nearest to the WALT's default window size
20ms will be also 19999998 (3333333 * 6).

Change-Id: I08f9bd2dbecccbb683e4490d06d8b0da703d3ab2
Suggested-by: Joel Fernandes <joelaf@google.com>
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>
(cherry picked from commit d368c6faa19ba98d26e713d3bf258cc6466d8ac2)
Signed-off-by: Quentin Perret <quentin.perret@arm.com>

kernel/sched/walt.c

diff --git a/kernel/sched/walt.c b/kernel/sched/walt.c
index 1d5e1d5..522f723 100644
--- a/kernel/sched/walt.c
+++ b/kernel/sched/walt.c
@@ -72,7 +72,15 @@
 __read_mostly unsigned int walt_ravg_window = 20000000;
 
 /* Min window size (in ns) = 10ms */
+#ifdef CONFIG_HZ_300
+/*
+ * Tick interval becomes to 3333333 due to
+ * rounding error when HZ=300.
+ */
+#define MIN_SCHED_RAVG_WINDOW (3333333 * 6)
+#else
 #define MIN_SCHED_RAVG_WINDOW 10000000
+#endif
 
 /* Max window size (in ns) = 1s */
 #define MAX_SCHED_RAVG_WINDOW 1000000000