sched/fair: Rename SCHED_LOAD_SHIFT to NICE_0_LOAD_SHIFT and remove SCHED_LOAD_SCALE

After cleaning up the sched metrics, there are two definitions that are
ambiguous and confusing: SCHED_LOAD_SHIFT and SCHED_LOAD_SHIFT.

Resolve this:

 - Rename SCHED_LOAD_SHIFT to NICE_0_LOAD_SHIFT, which better reflects what
   it is.

 - Replace SCHED_LOAD_SCALE use with SCHED_CAPACITY_SCALE and remove SCHED_LOAD_SCALE.

Suggested-by: Ben Segall <bsegall@google.com>
Signed-off-by: Yuyang Du <yuyang.du@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: lizefan@huawei.com
Cc: morten.rasmussen@arm.com
Cc: pjt@google.com
Cc: umgwanakikbuti@gmail.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1459829551-21625-3-git-send-email-yuyang.du@intel.com
[ Rewrote the changelog and fixed the build on 32-bit kernels. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 76ca86e..e148571 100644 (file)
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -719,7 +719,7 @@ void post_init_entity_util_avg(struct sched_entity *se)
 {
        struct cfs_rq *cfs_rq = cfs_rq_of(se);
        struct sched_avg *sa = &se->avg;
-       long cap = (long)(scale_load_down(SCHED_LOAD_SCALE) - cfs_rq->avg.util_avg) / 2;
+       long cap = (long)(SCHED_CAPACITY_SCALE - cfs_rq->avg.util_avg) / 2;
 
        if (cap > 0) {
                if (cfs_rq->avg.util_avg != 0) {
@@ -7010,7 +7010,7 @@ static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *s
        if (busiest->group_type == group_overloaded &&
            local->group_type   == group_overloaded) {
                load_above_capacity = busiest->sum_nr_running *
-                                       SCHED_LOAD_SCALE;
+                                     scale_load_down(NICE_0_LOAD);
                if (load_above_capacity > busiest->group_capacity)
                        load_above_capacity -= busiest->group_capacity;
                else

diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index ad83361..d24e91b 100644 (file)
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -56,25 +56,25 @@ static inline void cpu_load_update_active(struct rq *this_rq) { }
  * increase coverage and consistency always enable it on 64bit platforms.
  */
 #ifdef CONFIG_64BIT
-# define SCHED_LOAD_SHIFT      (SCHED_FIXEDPOINT_SHIFT + SCHED_FIXEDPOINT_SHIFT)
+# define NICE_0_LOAD_SHIFT     (SCHED_FIXEDPOINT_SHIFT + SCHED_FIXEDPOINT_SHIFT)
 # define scale_load(w)         ((w) << SCHED_FIXEDPOINT_SHIFT)
 # define scale_load_down(w)    ((w) >> SCHED_FIXEDPOINT_SHIFT)
 #else
-# define SCHED_LOAD_SHIFT      (SCHED_FIXEDPOINT_SHIFT)
+# define NICE_0_LOAD_SHIFT     (SCHED_FIXEDPOINT_SHIFT)
 # define scale_load(w)         (w)
 # define scale_load_down(w)    (w)
 #endif
 
-#define SCHED_LOAD_SCALE       (1L << SCHED_LOAD_SHIFT)
-
 /*
- * NICE_0's weight (visible to users) and its load (invisible to users) have
- * independent ranges, but they should be well calibrated. We use scale_load()
- * and scale_load_down(w) to convert between them, and the following must be true:
- * scale_load(sched_prio_to_weight[20]) == NICE_0_LOAD
+ * Task weight (visible to users) and its load (invisible to users) have
+ * independent resolution, but they should be well calibrated. We use
+ * scale_load() and scale_load_down(w) to convert between them. The
+ * following must be true:
+ *
+ *  scale_load(sched_prio_to_weight[USER_PRIO(NICE_TO_PRIO(0))]) == NICE_0_LOAD
+ *
  */
-#define NICE_0_LOAD            SCHED_LOAD_SCALE
-#define NICE_0_SHIFT           SCHED_LOAD_SHIFT
+#define NICE_0_LOAD            (1L << NICE_0_LOAD_SHIFT)
 
 /*
  * Single value that decides SCHED_DEADLINE internal math precision.
@@ -863,7 +863,7 @@ DECLARE_PER_CPU(struct sched_domain *, sd_asym);
 struct sched_group_capacity {
        atomic_t ref;
        /*
-        * CPU capacity of this group, SCHED_LOAD_SCALE being max capacity
+        * CPU capacity of this group, SCHED_CAPACITY_SCALE being max capacity
         * for a single CPU.
         */
        unsigned int capacity;