sched: cfs, add load-calculation methods
add the new load-calculation methods of CFS.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/sched.c b/kernel/sched.c
index 5cd069b..6e5a89b 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -671,6 +671,108 @@
#include "sched_stats.h"
+static u64 div64_likely32(u64 divident, unsigned long divisor)
+{
+#if BITS_PER_LONG == 32
+ if (likely(divident <= 0xffffffffULL))
+ return (u32)divident / divisor;
+ do_div(divident, divisor);
+
+ return divident;
+#else
+ return divident / divisor;
+#endif
+}
+
+#if BITS_PER_LONG == 32
+# define WMULT_CONST (~0UL)
+#else
+# define WMULT_CONST (1UL << 32)
+#endif
+
+#define WMULT_SHIFT 32
+
+static inline unsigned long
+calc_delta_mine(unsigned long delta_exec, unsigned long weight,
+ struct load_weight *lw)
+{
+ u64 tmp;
+
+ if (unlikely(!lw->inv_weight))
+ lw->inv_weight = WMULT_CONST / lw->weight;
+
+ tmp = (u64)delta_exec * weight;
+ /*
+ * Check whether we'd overflow the 64-bit multiplication:
+ */
+ if (unlikely(tmp > WMULT_CONST)) {
+ tmp = ((tmp >> WMULT_SHIFT/2) * lw->inv_weight)
+ >> (WMULT_SHIFT/2);
+ } else {
+ tmp = (tmp * lw->inv_weight) >> WMULT_SHIFT;
+ }
+
+ return (unsigned long)min(tmp, (u64)sysctl_sched_runtime_limit);
+}
+
+static inline unsigned long
+calc_delta_fair(unsigned long delta_exec, struct load_weight *lw)
+{
+ return calc_delta_mine(delta_exec, NICE_0_LOAD, lw);
+}
+
+static void update_load_add(struct load_weight *lw, unsigned long inc)
+{
+ lw->weight += inc;
+ lw->inv_weight = 0;
+}
+
+static void update_load_sub(struct load_weight *lw, unsigned long dec)
+{
+ lw->weight -= dec;
+ lw->inv_weight = 0;
+}
+
+static void __update_curr_load(struct rq *rq, struct load_stat *ls)
+{
+ if (rq->curr != rq->idle && ls->load.weight) {
+ ls->delta_exec += ls->delta_stat;
+ ls->delta_fair += calc_delta_fair(ls->delta_stat, &ls->load);
+ ls->delta_stat = 0;
+ }
+}
+
+/*
+ * Update delta_exec, delta_fair fields for rq.
+ *
+ * delta_fair clock advances at a rate inversely proportional to
+ * total load (rq->ls.load.weight) on the runqueue, while
+ * delta_exec advances at the same rate as wall-clock (provided
+ * cpu is not idle).
+ *
+ * delta_exec / delta_fair is a measure of the (smoothened) load on this
+ * runqueue over any given interval. This (smoothened) load is used
+ * during load balance.
+ *
+ * This function is called /before/ updating rq->ls.load
+ * and when switching tasks.
+ */
+static void update_curr_load(struct rq *rq, u64 now)
+{
+ struct load_stat *ls = &rq->ls;
+ u64 start;
+
+ start = ls->load_update_start;
+ ls->load_update_start = now;
+ ls->delta_stat += now - start;
+ /*
+ * Stagger updates to ls->delta_fair. Very frequent updates
+ * can be expensive.
+ */
+ if (ls->delta_stat >= sysctl_sched_stat_granularity)
+ __update_curr_load(rq, ls);
+}
+
/*
* To aid in avoiding the subversion of "niceness" due to uneven distribution
* of tasks with abnormal "nice" values across CPUs the contribution that
@@ -693,24 +795,6 @@
#define RTPRIO_TO_LOAD_WEIGHT(rp) \
(PRIO_TO_LOAD_WEIGHT(MAX_RT_PRIO) + LOAD_WEIGHT(rp))
-static void set_load_weight(struct task_struct *p)
-{
- if (task_has_rt_policy(p)) {
-#ifdef CONFIG_SMP
- if (p == task_rq(p)->migration_thread)
- /*
- * The migration thread does the actual balancing.
- * Giving its load any weight will skew balancing
- * adversely.
- */
- p->load_weight = 0;
- else
-#endif
- p->load_weight = RTPRIO_TO_LOAD_WEIGHT(p->rt_priority);
- } else
- p->load_weight = PRIO_TO_LOAD_WEIGHT(p->static_prio);
-}
-
static inline void
inc_raw_weighted_load(struct rq *rq, const struct task_struct *p)
{
@@ -735,6 +819,24 @@
dec_raw_weighted_load(rq, p);
}
+static void set_load_weight(struct task_struct *p)
+{
+ if (task_has_rt_policy(p)) {
+#ifdef CONFIG_SMP
+ if (p == task_rq(p)->migration_thread)
+ /*
+ * The migration thread does the actual balancing.
+ * Giving its load any weight will skew balancing
+ * adversely.
+ */
+ p->load_weight = 0;
+ else
+#endif
+ p->load_weight = RTPRIO_TO_LOAD_WEIGHT(p->rt_priority);
+ } else
+ p->load_weight = PRIO_TO_LOAD_WEIGHT(p->static_prio);
+}
+
/*
* Adding/removing a task to/from a priority array:
*/