sched: Move SCHED_LOAD_SHIFT macros to kernel/sched/sched.h

They are used internally only.

Signed-off-by: Li Zefan <lizefan@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/5135A771.4070104@huawei.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 25 insertions, 1 deletions

diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index cc03cfdf469..709a30cdfd8 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -33,6 +33,31 @@ extern __read_mostly int scheduler_running;
  */
 #define NS_TO_JIFFIES(TIME)	((unsigned long)(TIME) / (NSEC_PER_SEC / HZ))
 
+/*
+ * Increase resolution of nice-level calculations for 64-bit architectures.
+ * The extra resolution improves shares distribution and load balancing of
+ * low-weight task groups (eg. nice +19 on an autogroup), deeper taskgroup
+ * hierarchies, especially on larger systems. This is not a user-visible change
+ * and does not change the user-interface for setting shares/weights.
+ *
+ * We increase resolution only if we have enough bits to allow this increased
+ * resolution (i.e. BITS_PER_LONG > 32). The costs for increasing resolution
+ * when BITS_PER_LONG <= 32 are pretty high and the returns do not justify the
+ * increased costs.
+ */
+#if 0 /* BITS_PER_LONG > 32 -- currently broken: it increases power usage under light load  */
+# define SCHED_LOAD_RESOLUTION	10
+# define scale_load(w)		((w) << SCHED_LOAD_RESOLUTION)
+# define scale_load_down(w)	((w) >> SCHED_LOAD_RESOLUTION)
+#else
+# define SCHED_LOAD_RESOLUTION	0
+# define scale_load(w)		(w)
+# define scale_load_down(w)	(w)
+#endif
+
+#define SCHED_LOAD_SHIFT	(10 + SCHED_LOAD_RESOLUTION)
+#define SCHED_LOAD_SCALE	(1L << SCHED_LOAD_SHIFT)
+
 #define NICE_0_LOAD		SCHED_LOAD_SCALE
 #define NICE_0_SHIFT		SCHED_LOAD_SHIFT
 
@@ -784,7 +809,6 @@ static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev)
 }
 #endif /* __ARCH_WANT_UNLOCKED_CTXSW */
 
-
 static inline void update_load_add(struct load_weight *lw, unsigned long inc)
 {
 	lw->weight += inc;