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-rw-r--r--kernel/sched/fair.c1049
1 files changed, 690 insertions, 359 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 5c09ddf8c832..0989676c50e9 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -33,6 +33,7 @@
#include <linux/mempolicy.h>
#include <linux/migrate.h>
#include <linux/task_work.h>
+#include <linux/sched/isolation.h>
#include <trace/events/sched.h>
@@ -717,13 +718,8 @@ void init_entity_runnable_average(struct sched_entity *se)
{
struct sched_avg *sa = &se->avg;
- sa->last_update_time = 0;
- /*
- * sched_avg's period_contrib should be strictly less then 1024, so
- * we give it 1023 to make sure it is almost a period (1024us), and
- * will definitely be update (after enqueue).
- */
- sa->period_contrib = 1023;
+ memset(sa, 0, sizeof(*sa));
+
/*
* Tasks are intialized with full load to be seen as heavy tasks until
* they get a chance to stabilize to their real load level.
@@ -731,13 +727,10 @@ void init_entity_runnable_average(struct sched_entity *se)
* nothing has been attached to the task group yet.
*/
if (entity_is_task(se))
- sa->load_avg = scale_load_down(se->load.weight);
- sa->load_sum = sa->load_avg * LOAD_AVG_MAX;
- /*
- * At this point, util_avg won't be used in select_task_rq_fair anyway
- */
- sa->util_avg = 0;
- sa->util_sum = 0;
+ sa->runnable_load_avg = sa->load_avg = scale_load_down(se->load.weight);
+
+ se->runnable_weight = se->load.weight;
+
/* when this task enqueue'ed, it will contribute to its cfs_rq's load_avg */
}
@@ -785,7 +778,6 @@ void post_init_entity_util_avg(struct sched_entity *se)
} else {
sa->util_avg = cap;
}
- sa->util_sum = sa->util_avg * LOAD_AVG_MAX;
}
if (entity_is_task(se)) {
@@ -2026,7 +2018,7 @@ static u64 numa_get_avg_runtime(struct task_struct *p, u64 *period)
delta = runtime - p->last_sum_exec_runtime;
*period = now - p->last_task_numa_placement;
} else {
- delta = p->se.avg.load_sum / p->se.load.weight;
+ delta = p->se.avg.load_sum;
*period = LOAD_AVG_MAX;
}
@@ -2693,18 +2685,226 @@ account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
cfs_rq->nr_running--;
}
+/*
+ * Signed add and clamp on underflow.
+ *
+ * Explicitly do a load-store to ensure the intermediate value never hits
+ * memory. This allows lockless observations without ever seeing the negative
+ * values.
+ */
+#define add_positive(_ptr, _val) do { \
+ typeof(_ptr) ptr = (_ptr); \
+ typeof(_val) val = (_val); \
+ typeof(*ptr) res, var = READ_ONCE(*ptr); \
+ \
+ res = var + val; \
+ \
+ if (val < 0 && res > var) \
+ res = 0; \
+ \
+ WRITE_ONCE(*ptr, res); \
+} while (0)
+
+/*
+ * Unsigned subtract and clamp on underflow.
+ *
+ * Explicitly do a load-store to ensure the intermediate value never hits
+ * memory. This allows lockless observations without ever seeing the negative
+ * values.
+ */
+#define sub_positive(_ptr, _val) do { \
+ typeof(_ptr) ptr = (_ptr); \
+ typeof(*ptr) val = (_val); \
+ typeof(*ptr) res, var = READ_ONCE(*ptr); \
+ res = var - val; \
+ if (res > var) \
+ res = 0; \
+ WRITE_ONCE(*ptr, res); \
+} while (0)
+
+#ifdef CONFIG_SMP
+/*
+ * XXX we want to get rid of these helpers and use the full load resolution.
+ */
+static inline long se_weight(struct sched_entity *se)
+{
+ return scale_load_down(se->load.weight);
+}
+
+static inline long se_runnable(struct sched_entity *se)
+{
+ return scale_load_down(se->runnable_weight);
+}
+
+static inline void
+enqueue_runnable_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+ cfs_rq->runnable_weight += se->runnable_weight;
+
+ cfs_rq->avg.runnable_load_avg += se->avg.runnable_load_avg;
+ cfs_rq->avg.runnable_load_sum += se_runnable(se) * se->avg.runnable_load_sum;
+}
+
+static inline void
+dequeue_runnable_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+ cfs_rq->runnable_weight -= se->runnable_weight;
+
+ sub_positive(&cfs_rq->avg.runnable_load_avg, se->avg.runnable_load_avg);
+ sub_positive(&cfs_rq->avg.runnable_load_sum,
+ se_runnable(se) * se->avg.runnable_load_sum);
+}
+
+static inline void
+enqueue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+ cfs_rq->avg.load_avg += se->avg.load_avg;
+ cfs_rq->avg.load_sum += se_weight(se) * se->avg.load_sum;
+}
+
+static inline void
+dequeue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+ sub_positive(&cfs_rq->avg.load_avg, se->avg.load_avg);
+ sub_positive(&cfs_rq->avg.load_sum, se_weight(se) * se->avg.load_sum);
+}
+#else
+static inline void
+enqueue_runnable_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) { }
+static inline void
+dequeue_runnable_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) { }
+static inline void
+enqueue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) { }
+static inline void
+dequeue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) { }
+#endif
+
+static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
+ unsigned long weight, unsigned long runnable)
+{
+ if (se->on_rq) {
+ /* commit outstanding execution time */
+ if (cfs_rq->curr == se)
+ update_curr(cfs_rq);
+ account_entity_dequeue(cfs_rq, se);
+ dequeue_runnable_load_avg(cfs_rq, se);
+ }
+ dequeue_load_avg(cfs_rq, se);
+
+ se->runnable_weight = runnable;
+ update_load_set(&se->load, weight);
+
+#ifdef CONFIG_SMP
+ do {
+ u32 divider = LOAD_AVG_MAX - 1024 + se->avg.period_contrib;
+
+ se->avg.load_avg = div_u64(se_weight(se) * se->avg.load_sum, divider);
+ se->avg.runnable_load_avg =
+ div_u64(se_runnable(se) * se->avg.runnable_load_sum, divider);
+ } while (0);
+#endif
+
+ enqueue_load_avg(cfs_rq, se);
+ if (se->on_rq) {
+ account_entity_enqueue(cfs_rq, se);
+ enqueue_runnable_load_avg(cfs_rq, se);
+ }
+}
+
+void reweight_task(struct task_struct *p, int prio)
+{
+ struct sched_entity *se = &p->se;
+ struct cfs_rq *cfs_rq = cfs_rq_of(se);
+ struct load_weight *load = &se->load;
+ unsigned long weight = scale_load(sched_prio_to_weight[prio]);
+
+ reweight_entity(cfs_rq, se, weight, weight);
+ load->inv_weight = sched_prio_to_wmult[prio];
+}
+
#ifdef CONFIG_FAIR_GROUP_SCHED
# ifdef CONFIG_SMP
-static long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg)
+/*
+ * All this does is approximate the hierarchical proportion which includes that
+ * global sum we all love to hate.
+ *
+ * That is, the weight of a group entity, is the proportional share of the
+ * group weight based on the group runqueue weights. That is:
+ *
+ * tg->weight * grq->load.weight
+ * ge->load.weight = ----------------------------- (1)
+ * \Sum grq->load.weight
+ *
+ * Now, because computing that sum is prohibitively expensive to compute (been
+ * there, done that) we approximate it with this average stuff. The average
+ * moves slower and therefore the approximation is cheaper and more stable.
+ *
+ * So instead of the above, we substitute:
+ *
+ * grq->load.weight -> grq->avg.load_avg (2)
+ *
+ * which yields the following:
+ *
+ * tg->weight * grq->avg.load_avg
+ * ge->load.weight = ------------------------------ (3)
+ * tg->load_avg
+ *
+ * Where: tg->load_avg ~= \Sum grq->avg.load_avg
+ *
+ * That is shares_avg, and it is right (given the approximation (2)).
+ *
+ * The problem with it is that because the average is slow -- it was designed
+ * to be exactly that of course -- this leads to transients in boundary
+ * conditions. In specific, the case where the group was idle and we start the
+ * one task. It takes time for our CPU's grq->avg.load_avg to build up,
+ * yielding bad latency etc..
+ *
+ * Now, in that special case (1) reduces to:
+ *
+ * tg->weight * grq->load.weight
+ * ge->load.weight = ----------------------------- = tg->weight (4)
+ * grp->load.weight
+ *
+ * That is, the sum collapses because all other CPUs are idle; the UP scenario.
+ *
+ * So what we do is modify our approximation (3) to approach (4) in the (near)
+ * UP case, like:
+ *
+ * ge->load.weight =
+ *
+ * tg->weight * grq->load.weight
+ * --------------------------------------------------- (5)
+ * tg->load_avg - grq->avg.load_avg + grq->load.weight
+ *
+ * But because grq->load.weight can drop to 0, resulting in a divide by zero,
+ * we need to use grq->avg.load_avg as its lower bound, which then gives:
+ *
+ *
+ * tg->weight * grq->load.weight
+ * ge->load.weight = ----------------------------- (6)
+ * tg_load_avg'
+ *
+ * Where:
+ *
+ * tg_load_avg' = tg->load_avg - grq->avg.load_avg +
+ * max(grq->load.weight, grq->avg.load_avg)
+ *
+ * And that is shares_weight and is icky. In the (near) UP case it approaches
+ * (4) while in the normal case it approaches (3). It consistently
+ * overestimates the ge->load.weight and therefore:
+ *
+ * \Sum ge->load.weight >= tg->weight
+ *
+ * hence icky!
+ */
+static long calc_group_shares(struct cfs_rq *cfs_rq)
{
- long tg_weight, load, shares;
+ long tg_weight, tg_shares, load, shares;
+ struct task_group *tg = cfs_rq->tg;
- /*
- * This really should be: cfs_rq->avg.load_avg, but instead we use
- * cfs_rq->load.weight, which is its upper bound. This helps ramp up
- * the shares for small weight interactive tasks.
- */
- load = scale_load_down(cfs_rq->load.weight);
+ tg_shares = READ_ONCE(tg->shares);
+
+ load = max(scale_load_down(cfs_rq->load.weight), cfs_rq->avg.load_avg);
tg_weight = atomic_long_read(&tg->load_avg);
@@ -2712,7 +2912,7 @@ static long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg)
tg_weight -= cfs_rq->tg_load_avg_contrib;
tg_weight += load;
- shares = (tg->shares * load);
+ shares = (tg_shares * load);
if (tg_weight)
shares /= tg_weight;
@@ -2728,63 +2928,86 @@ static long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg)
* case no task is runnable on a CPU MIN_SHARES=2 should be returned
* instead of 0.
*/
- if (shares < MIN_SHARES)
- shares = MIN_SHARES;
- if (shares > tg->shares)
- shares = tg->shares;
-
- return shares;
-}
-# else /* CONFIG_SMP */
-static inline long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg)
-{
- return tg->shares;
+ return clamp_t(long, shares, MIN_SHARES, tg_shares);
}
-# endif /* CONFIG_SMP */
-static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
- unsigned long weight)
+/*
+ * This calculates the effective runnable weight for a group entity based on
+ * the group entity weight calculated above.
+ *
+ * Because of the above approximation (2), our group entity weight is
+ * an load_avg based ratio (3). This means that it includes blocked load and
+ * does not represent the runnable weight.
+ *
+ * Approximate the group entity's runnable weight per ratio from the group
+ * runqueue:
+ *
+ * grq->avg.runnable_load_avg
+ * ge->runnable_weight = ge->load.weight * -------------------------- (7)
+ * grq->avg.load_avg
+ *
+ * However, analogous to above, since the avg numbers are slow, this leads to
+ * transients in the from-idle case. Instead we use:
+ *
+ * ge->runnable_weight = ge->load.weight *
+ *
+ * max(grq->avg.runnable_load_avg, grq->runnable_weight)
+ * ----------------------------------------------------- (8)
+ * max(grq->avg.load_avg, grq->load.weight)
+ *
+ * Where these max() serve both to use the 'instant' values to fix the slow
+ * from-idle and avoid the /0 on to-idle, similar to (6).
+ */
+static long calc_group_runnable(struct cfs_rq *cfs_rq, long shares)
{
- if (se->on_rq) {
- /* commit outstanding execution time */
- if (cfs_rq->curr == se)
- update_curr(cfs_rq);
- account_entity_dequeue(cfs_rq, se);
- }
+ long runnable, load_avg;
- update_load_set(&se->load, weight);
+ load_avg = max(cfs_rq->avg.load_avg,
+ scale_load_down(cfs_rq->load.weight));
- if (se->on_rq)
- account_entity_enqueue(cfs_rq, se);
+ runnable = max(cfs_rq->avg.runnable_load_avg,
+ scale_load_down(cfs_rq->runnable_weight));
+
+ runnable *= shares;
+ if (load_avg)
+ runnable /= load_avg;
+
+ return clamp_t(long, runnable, MIN_SHARES, shares);
}
+# endif /* CONFIG_SMP */
static inline int throttled_hierarchy(struct cfs_rq *cfs_rq);
-static void update_cfs_shares(struct sched_entity *se)
+/*
+ * Recomputes the group entity based on the current state of its group
+ * runqueue.
+ */
+static void update_cfs_group(struct sched_entity *se)
{
- struct cfs_rq *cfs_rq = group_cfs_rq(se);
- struct task_group *tg;
- long shares;
+ struct cfs_rq *gcfs_rq = group_cfs_rq(se);
+ long shares, runnable;
- if (!cfs_rq)
+ if (!gcfs_rq)
return;
- if (throttled_hierarchy(cfs_rq))
+ if (throttled_hierarchy(gcfs_rq))
return;
- tg = cfs_rq->tg;
-
#ifndef CONFIG_SMP
- if (likely(se->load.weight == tg->shares))
+ runnable = shares = READ_ONCE(gcfs_rq->tg->shares);
+
+ if (likely(se->load.weight == shares))
return;
+#else
+ shares = calc_group_shares(gcfs_rq);
+ runnable = calc_group_runnable(gcfs_rq, shares);
#endif
- shares = calc_cfs_shares(cfs_rq, tg);
- reweight_entity(cfs_rq_of(se), se, shares);
+ reweight_entity(cfs_rq_of(se), se, shares, runnable);
}
#else /* CONFIG_FAIR_GROUP_SCHED */
-static inline void update_cfs_shares(struct sched_entity *se)
+static inline void update_cfs_group(struct sched_entity *se)
{
}
#endif /* CONFIG_FAIR_GROUP_SCHED */
@@ -2893,7 +3116,7 @@ static u32 __accumulate_pelt_segments(u64 periods, u32 d1, u32 d3)
*/
static __always_inline u32
accumulate_sum(u64 delta, int cpu, struct sched_avg *sa,
- unsigned long weight, int running, struct cfs_rq *cfs_rq)
+ unsigned long load, unsigned long runnable, int running)
{
unsigned long scale_freq, scale_cpu;
u32 contrib = (u32)delta; /* p == 0 -> delta < 1024 */
@@ -2910,10 +3133,8 @@ accumulate_sum(u64 delta, int cpu, struct sched_avg *sa,
*/
if (periods) {
sa->load_sum = decay_load(sa->load_sum, periods);
- if (cfs_rq) {
- cfs_rq->runnable_load_sum =
- decay_load(cfs_rq->runnable_load_sum, periods);
- }
+ sa->runnable_load_sum =
+ decay_load(sa->runnable_load_sum, periods);
sa->util_sum = decay_load((u64)(sa->util_sum), periods);
/*
@@ -2926,11 +3147,10 @@ accumulate_sum(u64 delta, int cpu, struct sched_avg *sa,
sa->period_contrib = delta;
contrib = cap_scale(contrib, scale_freq);
- if (weight) {
- sa->load_sum += weight * contrib;
- if (cfs_rq)
- cfs_rq->runnable_load_sum += weight * contrib;
- }
+ if (load)
+ sa->load_sum += load * contrib;
+ if (runnable)
+ sa->runnable_load_sum += runnable * contrib;
if (running)
sa->util_sum += contrib * scale_cpu;
@@ -2966,8 +3186,8 @@ accumulate_sum(u64 delta, int cpu, struct sched_avg *sa,
* = u_0 + u_1*y + u_2*y^2 + ... [re-labeling u_i --> u_{i+1}]
*/
static __always_inline int
-___update_load_avg(u64 now, int cpu, struct sched_avg *sa,
- unsigned long weight, int running, struct cfs_rq *cfs_rq)
+___update_load_sum(u64 now, int cpu, struct sched_avg *sa,
+ unsigned long load, unsigned long runnable, int running)
{
u64 delta;
@@ -3000,8 +3220,8 @@ ___update_load_avg(u64 now, int cpu, struct sched_avg *sa,
* this happens during idle_balance() which calls
* update_blocked_averages()
*/
- if (!weight)
- running = 0;
+ if (!load)
+ runnable = running = 0;
/*
* Now we know we crossed measurement unit boundaries. The *_avg
@@ -3010,63 +3230,96 @@ ___update_load_avg(u64 now, int cpu, struct sched_avg *sa,
* Step 1: accumulate *_sum since last_update_time. If we haven't
* crossed period boundaries, finish.
*/
- if (!accumulate_sum(delta, cpu, sa, weight, running, cfs_rq))
+ if (!accumulate_sum(delta, cpu, sa, load, runnable, running))
return 0;
+ return 1;
+}
+
+static __always_inline void
+___update_load_avg(struct sched_avg *sa, unsigned long load, unsigned long runnable)
+{
+ u32 divider = LOAD_AVG_MAX - 1024 + sa->period_contrib;
+
/*
* Step 2: update *_avg.
*/
- sa->load_avg = div_u64(sa->load_sum, LOAD_AVG_MAX - 1024 + sa->period_contrib);
- if (cfs_rq) {
- cfs_rq->runnable_load_avg =
- div_u64(cfs_rq->runnable_load_sum, LOAD_AVG_MAX - 1024 + sa->period_contrib);
- }
- sa->util_avg = sa->util_sum / (LOAD_AVG_MAX - 1024 + sa->period_contrib);
-
- return 1;
+ sa->load_avg = div_u64(load * sa->load_sum, divider);
+ sa->runnable_load_avg = div_u64(runnable * sa->runnable_load_sum, divider);
+ sa->util_avg = sa->util_sum / divider;
}
+/*
+ * sched_entity:
+ *
+ * task:
+ * se_runnable() == se_weight()
+ *
+ * group: [ see update_cfs_group() ]
+ * se_weight() = tg->weight * grq->load_avg / tg->load_avg
+ * se_runnable() = se_weight(se) * grq->runnable_load_avg / grq->load_avg
+ *
+ * load_sum := runnable_sum
+ * load_avg = se_weight(se) * runnable_avg
+ *
+ * runnable_load_sum := runnable_sum
+ * runnable_load_avg = se_runnable(se) * runnable_avg
+ *
+ * XXX collapse load_sum and runnable_load_sum
+ *
+ * cfq_rs:
+ *
+ * load_sum = \Sum se_weight(se) * se->avg.load_sum
+ * load_avg = \Sum se->avg.load_avg
+ *
+ * runnable_load_sum = \Sum se_runnable(se) * se->avg.runnable_load_sum
+ * runnable_load_avg = \Sum se->avg.runable_load_avg
+ */
+
static int
__update_load_avg_blocked_se(u64 now, int cpu, struct sched_entity *se)
{
- return ___update_load_avg(now, cpu, &se->avg, 0, 0, NULL);
+ if (entity_is_task(se))
+ se->runnable_weight = se->load.weight;
+
+ if (___update_load_sum(now, cpu, &se->avg, 0, 0, 0)) {
+ ___update_load_avg(&se->avg, se_weight(se), se_runnable(se));
+ return 1;
+ }
+
+ return 0;
}
static int
__update_load_avg_se(u64 now, int cpu, struct cfs_rq *cfs_rq, struct sched_entity *se)
{
- return ___update_load_avg(now, cpu, &se->avg,
- se->on_rq * scale_load_down(se->load.weight),
- cfs_rq->curr == se, NULL);
+ if (entity_is_task(se))
+ se->runnable_weight = se->load.weight;
+
+ if (___update_load_sum(now, cpu, &se->avg, !!se->on_rq, !!se->on_rq,
+ cfs_rq->curr == se)) {
+
+ ___update_load_avg(&se->avg, se_weight(se), se_runnable(se));
+ return 1;
+ }
+
+ return 0;
}
static int
__update_load_avg_cfs_rq(u64 now, int cpu, struct cfs_rq *cfs_rq)
{
- return ___update_load_avg(now, cpu, &cfs_rq->avg,
- scale_load_down(cfs_rq->load.weight),
- cfs_rq->curr != NULL, cfs_rq);
-}
+ if (___update_load_sum(now, cpu, &cfs_rq->avg,
+ scale_load_down(cfs_rq->load.weight),
+ scale_load_down(cfs_rq->runnable_weight),
+ cfs_rq->curr != NULL)) {
-/*
- * Signed add and clamp on underflow.
- *
- * Explicitly do a load-store to ensure the intermediate value never hits
- * memory. This allows lockless observations without ever seeing the negative
- * values.
- */
-#define add_positive(_ptr, _val) do { \
- typeof(_ptr) ptr = (_ptr); \
- typeof(_val) val = (_val); \
- typeof(*ptr) res, var = READ_ONCE(*ptr); \
- \
- res = var + val; \
- \
- if (val < 0 && res > var) \
- res = 0; \
- \
- WRITE_ONCE(*ptr, res); \
-} while (0)
+ ___update_load_avg(&cfs_rq->avg, 1, 1);
+ return 1;
+ }
+
+ return 0;
+}
#ifdef CONFIG_FAIR_GROUP_SCHED
/**
@@ -3149,11 +3402,77 @@ void set_task_rq_fair(struct sched_entity *se,
se->avg.last_update_time = n_last_update_time;
}
-/* Take into account change of utilization of a child task group */
+
+/*
+ * When on migration a sched_entity joins/leaves the PELT hierarchy, we need to
+ * propagate its contribution. The key to this propagation is the invariant
+ * that for each group:
+ *
+ * ge->avg == grq->avg (1)
+ *
+ * _IFF_ we look at the pure running and runnable sums. Because they
+ * represent the very same entity, just at different points in the hierarchy.
+ *
+ *
+ * Per the above update_tg_cfs_util() is trivial (and still 'wrong') and
+ * simply copies the running sum over.
+ *
+ * However, update_tg_cfs_runnable() is more complex. So we have:
+ *
+ * ge->avg.load_avg = ge->load.weight * ge->avg.runnable_avg (2)
+ *
+ * And since, like util, the runnable part should be directly transferable,
+ * the following would _appear_ to be the straight forward approach:
+ *
+ * grq->avg.load_avg = grq->load.weight * grq->avg.running_avg (3)
+ *
+ * And per (1) we have:
+ *
+ * ge->avg.running_avg == grq->avg.running_avg
+ *
+ * Which gives:
+ *
+ * ge->load.weight * grq->avg.load_avg
+ * ge->avg.load_avg = ----------------------------------- (4)
+ * grq->load.weight
+ *
+ * Except that is wrong!
+ *
+ * Because while for entities historical weight is not important and we
+ * really only care about our future and therefore can consider a pure
+ * runnable sum, runqueues can NOT do this.
+ *
+ * We specifically want runqueues to have a load_avg that includes
+ * historical weights. Those represent the blocked load, the load we expect
+ * to (shortly) return to us. This only works by keeping the weights as
+ * integral part of the sum. We therefore cannot decompose as per (3).
+ *
+ * OK, so what then?
+ *
+ *
+ * Another way to look at things is:
+ *
+ * grq->avg.load_avg = \Sum se->avg.load_avg
+ *
+ * Therefore, per (2):
+ *
+ * grq->avg.load_avg = \Sum se->load.weight * se->avg.runnable_avg
+ *
+ * And the very thing we're propagating is a change in that sum (someone
+ * joined/left). So we can easily know the runnable change, which would be, per
+ * (2) the already tracked se->load_avg divided by the corresponding
+ * se->weight.
+ *
+ * Basically (4) but in differential form:
+ *
+ * d(runnable_avg) += se->avg.load_avg / se->load.weight
+ * (5)
+ * ge->avg.load_avg += ge->load.weight * d(runnable_avg)
+ */
+
static inline void
-update_tg_cfs_util(struct cfs_rq *cfs_rq, struct sched_entity *se)
+update_tg_cfs_util(struct cfs_rq *cfs_rq, struct sched_entity *se, struct cfs_rq *gcfs_rq)
{
- struct cfs_rq *gcfs_rq = group_cfs_rq(se);
long delta = gcfs_rq->avg.util_avg - se->avg.util_avg;
/* Nothing to update */
@@ -3169,102 +3488,65 @@ update_tg_cfs_util(struct cfs_rq *cfs_rq, struct sched_entity *se)
cfs_rq->avg.util_sum = cfs_rq->avg.util_avg * LOAD_AVG_MAX;
}
-/* Take into account change of load of a child task group */
static inline void
-update_tg_cfs_load(struct cfs_rq *cfs_rq, struct sched_entity *se)
+update_tg_cfs_runnable(struct cfs_rq *cfs_rq, struct sched_entity *se, struct cfs_rq *gcfs_rq)
{
- struct cfs_rq *gcfs_rq = group_cfs_rq(se);
- long delta, load = gcfs_rq->avg.load_avg;
+ long runnable_sum = gcfs_rq->prop_runnable_sum;
+ long runnable_load_avg, load_avg;
+ s64 runnable_load_sum, load_sum;
- /*
- * If the load of group cfs_rq is null, the load of the
- * sched_entity will also be null so we can skip the formula
- */
- if (load) {
- long tg_load;
+ if (!runnable_sum)
+ return;
- /* Get tg's load and ensure tg_load > 0 */
- tg_load = atomic_long_read(&gcfs_rq->tg->load_avg) + 1;
+ gcfs_rq->prop_runnable_sum = 0;
- /* Ensure tg_load >= load and updated with current load*/
- tg_load -= gcfs_rq->tg_load_avg_contrib;
- tg_load += load;
+ load_sum = (s64)se_weight(se) * runnable_sum;
+ load_avg = div_s64(load_sum, LOAD_AVG_MAX);
- /*
- * We need to compute a correction term in the case that the
- * task group is consuming more CPU than a task of equal
- * weight. A task with a weight equals to tg->shares will have
- * a load less or equal to scale_load_down(tg->shares).
- * Similarly, the sched_entities that represent the task group
- * at parent level, can't have a load higher than
- * scale_load_down(tg->shares). And the Sum of sched_entities'
- * load must be <= scale_load_down(tg->shares).
- */
- if (tg_load > scale_load_down(gcfs_rq->tg->shares)) {
- /* scale gcfs_rq's load into tg's shares*/
- load *= scale_load_down(gcfs_rq->tg->shares);
- load /= tg_load;
- }
- }
+ add_positive(&se->avg.load_sum, runnable_sum);
+ add_positive(&se->avg.load_avg, load_avg);
- delta = load - se->avg.load_avg;
+ add_positive(&cfs_rq->avg.load_avg, load_avg);
+ add_positive(&cfs_rq->avg.load_sum, load_sum);
- /* Nothing to update */
- if (!delta)
- return;
-
- /* Set new sched_entity's load */
- se->avg.load_avg = load;
- se->avg.load_sum = se->avg.load_avg * LOAD_AVG_MAX;
+ runnable_load_sum = (s64)se_runnable(se) * runnable_sum;
+ runnable_load_avg = div_s64(runnable_load_sum, LOAD_AVG_MAX);
- /* Update parent cfs_rq load */
- add_positive(&cfs_rq->avg.load_avg, delta);
- cfs_rq->avg.load_sum = cfs_rq->avg.load_avg * LOAD_AVG_MAX;
+ add_positive(&se->avg.runnable_load_sum, runnable_sum);
+ add_positive(&se->avg.runnable_load_avg, runnable_load_avg);
- /*
- * If the sched_entity is already enqueued, we also have to update the
- * runnable load avg.
- */
if (se->on_rq) {
- /* Update parent cfs_rq runnable_load_avg */
- add_positive(&cfs_rq->runnable_load_avg, delta);
- cfs_rq->runnable_load_sum = cfs_rq->runnable_load_avg * LOAD_AVG_MAX;
+ add_positive(&cfs_rq->avg.runnable_load_avg, runnable_load_avg);
+ add_positive(&cfs_rq->avg.runnable_load_sum, runnable_load_sum);
}
}
-static inline void set_tg_cfs_propagate(struct cfs_rq *cfs_rq)
-{
- cfs_rq->propagate_avg = 1;
-}
-
-static inline int test_and_clear_tg_cfs_propagate(struct sched_entity *se)
+static inline void add_tg_cfs_propagate(struct cfs_rq *cfs_rq, long runnable_sum)
{
- struct cfs_rq *cfs_rq = group_cfs_rq(se);
-
- if (!cfs_rq->propagate_avg)
- return 0;
-
- cfs_rq->propagate_avg = 0;
- return 1;
+ cfs_rq->propagate = 1;
+ cfs_rq->prop_runnable_sum += runnable_sum;
}
/* Update task and its cfs_rq load average */
static inline int propagate_entity_load_avg(struct sched_entity *se)
{
- struct cfs_rq *cfs_rq;
+ struct cfs_rq *cfs_rq, *gcfs_rq;
if (entity_is_task(se))
return 0;
- if (!test_and_clear_tg_cfs_propagate(se))
+ gcfs_rq = group_cfs_rq(se);
+ if (!gcfs_rq->propagate)
return 0;
+ gcfs_rq->propagate = 0;
+
cfs_rq = cfs_rq_of(se);
- set_tg_cfs_propagate(cfs_rq);
+ add_tg_cfs_propagate(cfs_rq, gcfs_rq->prop_runnable_sum);
- update_tg_cfs_util(cfs_rq, se);
- update_tg_cfs_load(cfs_rq, se);
+ update_tg_cfs_util(cfs_rq, se, gcfs_rq);
+ update_tg_cfs_runnable(cfs_rq, se, gcfs_rq);
return 1;
}
@@ -3288,7 +3570,7 @@ static inline bool skip_blocked_update(struct sched_entity *se)
* If there is a pending propagation, we have to update the load and
* the utilization of the sched_entity:
*/
- if (gcfs_rq->propagate_avg)
+ if (gcfs_rq->propagate)
return false;
/*
@@ -3308,27 +3590,10 @@ static inline int propagate_entity_load_avg(struct sched_entity *se)
return 0;
}
-static inline void set_tg_cfs_propagate(struct cfs_rq *cfs_rq) {}
+static inline void add_tg_cfs_propagate(struct cfs_rq *cfs_rq, long runnable_sum) {}
#endif /* CONFIG_FAIR_GROUP_SCHED */
-/*
- * Unsigned subtract and clamp on underflow.
- *
- * Explicitly do a load-store to ensure the intermediate value never hits
- * memory. This allows lockless observations without ever seeing the negative
- * values.
- */
-#define sub_positive(_ptr, _val) do { \
- typeof(_ptr) ptr = (_ptr); \
- typeof(*ptr) val = (_val); \
- typeof(*ptr) res, var = READ_ONCE(*ptr); \
- res = var - val; \
- if (res > var) \
- res = 0; \
- WRITE_ONCE(*ptr, res); \
-} while (0)
-
/**
* update_cfs_rq_load_avg - update the cfs_rq's load/util averages
* @now: current time, as per cfs_rq_clock_task()
@@ -3348,65 +3613,45 @@ static inline void set_tg_cfs_propagate(struct cfs_rq *cfs_rq) {}
static inline int
update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq)
{
+ unsigned long removed_load = 0, removed_util = 0, removed_runnable_sum = 0;
struct sched_avg *sa = &cfs_rq->avg;
- int decayed, removed_load = 0, removed_util = 0;
+ int decayed = 0;
- if (atomic_long_read(&cfs_rq->removed_load_avg)) {
- s64 r = atomic_long_xchg(&cfs_rq->removed_load_avg, 0);
+ if (cfs_rq->removed.nr) {
+ unsigned long r;
+ u32 divider = LOAD_AVG_MAX - 1024 + sa->period_contrib;
+
+ raw_spin_lock(&cfs_rq->removed.lock);
+ swap(cfs_rq->removed.util_avg, removed_util);
+ swap(cfs_rq->removed.load_avg, removed_load);
+ swap(cfs_rq->removed.runnable_sum, removed_runnable_sum);
+ cfs_rq->removed.nr = 0;
+ raw_spin_unlock(&cfs_rq->removed.lock);
+
+ r = removed_load;
sub_positive(&sa->load_avg, r);
- sub_positive(&sa->load_sum, r * LOAD_AVG_MAX);
- removed_load = 1;
- set_tg_cfs_propagate(cfs_rq);
- }
+ sub_positive(&sa->load_sum, r * divider);
- if (atomic_long_read(&cfs_rq->removed_util_avg)) {
- long r = atomic_long_xchg(&cfs_rq->removed_util_avg, 0);
+ r = removed_util;
sub_positive(&sa->util_avg, r);
- sub_positive(&sa->util_sum, r * LOAD_AVG_MAX);
- removed_util = 1;
- set_tg_cfs_propagate(cfs_rq);
+ sub_positive(&sa->util_sum, r * divider);
+
+ add_tg_cfs_propagate(cfs_rq, -(long)removed_runnable_sum);
+
+ decayed = 1;
}
- decayed = __update_load_avg_cfs_rq(now, cpu_of(rq_of(cfs_rq)), cfs_rq);
+ decayed |= __update_load_avg_cfs_rq(now, cpu_of(rq_of(cfs_rq)), cfs_rq);
#ifndef CONFIG_64BIT
smp_wmb();
cfs_rq->load_last_update_time_copy = sa->last_update_time;
#endif
- if (decayed || removed_util)
+ if (decayed)
cfs_rq_util_change(cfs_rq);
- return decayed || removed_load;
-}
-
-/*
- * Optional action to be done while updating the load average
- */
-#define UPDATE_TG 0x1
-#define SKIP_AGE_LOAD 0x2
-
-/* Update task and its cfs_rq load average */
-static inline void update_load_avg(struct sched_entity *se, int flags)
-{
- struct cfs_rq *cfs_rq = cfs_rq_of(se);
- u64 now = cfs_rq_clock_task(cfs_rq);
- struct rq *rq = rq_of(cfs_rq);
- int cpu = cpu_of(rq);
- int decayed;
-
- /*
- * Track task load average for carrying it to new CPU after migrated, and
- * track group sched_entity load average for task_h_load calc in migration
- */
- if (se->avg.last_update_time && !(flags & SKIP_AGE_LOAD))
- __update_load_avg_se(now, cpu, cfs_rq, se);
-
- decayed = update_cfs_rq_load_avg(now, cfs_rq);
- decayed |= propagate_entity_load_avg(se);
-
- if (decayed && (flags & UPDATE_TG))
- update_tg_load_avg(cfs_rq, 0);
+ return decayed;
}
/**
@@ -3419,12 +3664,39 @@ static inline void update_load_avg(struct sched_entity *se, int flags)
*/
static void attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
+ u32 divider = LOAD_AVG_MAX - 1024 + cfs_rq->avg.period_contrib;
+
+ /*
+ * When we attach the @se to the @cfs_rq, we must align the decay
+ * window because without that, really weird and wonderful things can
+ * happen.
+ *
+ * XXX illustrate
+ */
se->avg.last_update_time = cfs_rq->avg.last_update_time;
- cfs_rq->avg.load_avg += se->avg.load_avg;
- cfs_rq->avg.load_sum += se->avg.load_sum;
+ se->avg.period_contrib = cfs_rq->avg.period_contrib;
+
+ /*
+ * Hell(o) Nasty stuff.. we need to recompute _sum based on the new
+ * period_contrib. This isn't strictly correct, but since we're
+ * entirely outside of the PELT hierarchy, nobody cares if we truncate
+ * _sum a little.
+ */
+ se->avg.util_sum = se->avg.util_avg * divider;
+
+ se->avg.load_sum = divider;
+ if (se_weight(se)) {
+ se->avg.load_sum =
+ div_u64(se->avg.load_avg * se->avg.load_sum, se_weight(se));
+ }
+
+ se->avg.runnable_load_sum = se->avg.load_sum;
+
+ enqueue_load_avg(cfs_rq, se);
cfs_rq->avg.util_avg += se->avg.util_avg;
cfs_rq->avg.util_sum += se->avg.util_sum;
- set_tg_cfs_propagate(cfs_rq);
+
+ add_tg_cfs_propagate(cfs_rq, se->avg.load_sum);
cfs_rq_util_change(cfs_rq);
}
@@ -3439,39 +3711,47 @@ static void attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *s
*/
static void detach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
-
- sub_positive(&cfs_rq->avg.load_avg, se->avg.load_avg);
- sub_positive(&cfs_rq->avg.load_sum, se->avg.load_sum);
+ dequeue_load_avg(cfs_rq, se);
sub_positive(&cfs_rq->avg.util_avg, se->avg.util_avg);
sub_positive(&cfs_rq->avg.util_sum, se->avg.util_sum);
- set_tg_cfs_propagate(cfs_rq);
+
+ add_tg_cfs_propagate(cfs_rq, -se->avg.load_sum);
cfs_rq_util_change(cfs_rq);
}
-/* Add the load generated by se into cfs_rq's load average */
-static inline void
-enqueue_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
+/*
+ * Optional action to be done while updating the load average
+ */
+#define UPDATE_TG 0x1
+#define SKIP_AGE_LOAD 0x2
+#define DO_ATTACH 0x4
+
+/* Update task and its cfs_rq load average */
+static inline void update_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
{
- struct sched_avg *sa = &se->avg;
+ u64 now = cfs_rq_clock_task(cfs_rq);
+ struct rq *rq = rq_of(cfs_rq);
+ int cpu = cpu_of(rq);
+ int decayed;
+
+ /*
+ * Track task load average for carrying it to new CPU after migrated, and
+ * track group sched_entity load average for task_h_load calc in migration
+ */
+ if (se->avg.last_update_time && !(flags & SKIP_AGE_LOAD))
+ __update_load_avg_se(now, cpu, cfs_rq, se);
- cfs_rq->runnable_load_avg += sa->load_avg;
- cfs_rq->runnable_load_sum += sa->load_sum;
+ decayed = update_cfs_rq_load_avg(now, cfs_rq);
+ decayed |= propagate_entity_load_avg(se);
+
+ if (!se->avg.last_update_time && (flags & DO_ATTACH)) {
- if (!sa->last_update_time) {
attach_entity_load_avg(cfs_rq, se);
update_tg_load_avg(cfs_rq, 0);
- }
-}
-/* Remove the runnable load generated by se from cfs_rq's runnable load average */
-static inline void
-dequeue_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
-{
- cfs_rq->runnable_load_avg =
- max_t(long, cfs_rq->runnable_load_avg - se->avg.load_avg, 0);
- cfs_rq->runnable_load_sum =
- max_t(s64, cfs_rq->runnable_load_sum - se->avg.load_sum, 0);
+ } else if (decayed && (flags & UPDATE_TG))
+ update_tg_load_avg(cfs_rq, 0);
}
#ifndef CONFIG_64BIT
@@ -3515,6 +3795,7 @@ void sync_entity_load_avg(struct sched_entity *se)
void remove_entity_load_avg(struct sched_entity *se)
{
struct cfs_rq *cfs_rq = cfs_rq_of(se);
+ unsigned long flags;
/*
* tasks cannot exit without having gone through wake_up_new_task() ->
@@ -3527,13 +3808,18 @@ void remove_entity_load_avg(struct sched_entity *se)
*/
sync_entity_load_avg(se);
- atomic_long_add(se->avg.load_avg, &cfs_rq->removed_load_avg);
- atomic_long_add(se->avg.util_avg, &cfs_rq->removed_util_avg);
+
+ raw_spin_lock_irqsave(&cfs_rq->removed.lock, flags);
+ ++cfs_rq->removed.nr;
+ cfs_rq->removed.util_avg += se->avg.util_avg;
+ cfs_rq->removed.load_avg += se->avg.load_avg;
+ cfs_rq->removed.runnable_sum += se->avg.load_sum; /* == runnable_sum */
+ raw_spin_unlock_irqrestore(&cfs_rq->removed.lock, flags);
}
static inline unsigned long cfs_rq_runnable_load_avg(struct cfs_rq *cfs_rq)
{
- return cfs_rq->runnable_load_avg;
+ return cfs_rq->avg.runnable_load_avg;
}
static inline unsigned long cfs_rq_load_avg(struct cfs_rq *cfs_rq)
@@ -3553,16 +3839,13 @@ update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq)
#define UPDATE_TG 0x0
#define SKIP_AGE_LOAD 0x0
+#define DO_ATTACH 0x0
-static inline void update_load_avg(struct sched_entity *se, int not_used1)
+static inline void update_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se, int not_used1)
{
- cfs_rq_util_change(cfs_rq_of(se));
+ cfs_rq_util_change(cfs_rq);
}
-static inline void
-enqueue_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {}
-static inline void
-dequeue_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {}
static inline void remove_entity_load_avg(struct sched_entity *se) {}
static inline void
@@ -3707,9 +3990,9 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
* its group cfs_rq
* - Add its new weight to cfs_rq->load.weight
*/
- update_load_avg(se, UPDATE_TG);
- enqueue_entity_load_avg(cfs_rq, se);
- update_cfs_shares(se);
+ update_load_avg(cfs_rq, se, UPDATE_TG | DO_ATTACH);
+ update_cfs_group(se);
+ enqueue_runnable_load_avg(cfs_rq, se);
account_entity_enqueue(cfs_rq, se);
if (flags & ENQUEUE_WAKEUP)
@@ -3791,8 +4074,8 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
* - For group entity, update its weight to reflect the new share
* of its group cfs_rq.
*/
- update_load_avg(se, UPDATE_TG);
- dequeue_entity_load_avg(cfs_rq, se);
+ update_load_avg(cfs_rq, se, UPDATE_TG);
+ dequeue_runnable_load_avg(cfs_rq, se);
update_stats_dequeue(cfs_rq, se, flags);
@@ -3815,7 +4098,7 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
/* return excess runtime on last dequeue */
return_cfs_rq_runtime(cfs_rq);
- update_cfs_shares(se);
+ update_cfs_group(se);
/*
* Now advance min_vruntime if @se was the entity holding it back,
@@ -3879,7 +4162,7 @@ set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
*/
update_stats_wait_end(cfs_rq, se);
__dequeue_entity(cfs_rq, se);
- update_load_avg(se, UPDATE_TG);
+ update_load_avg(cfs_rq, se, UPDATE_TG);
}
update_stats_curr_start(cfs_rq, se);
@@ -3981,7 +4264,7 @@ static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev)
/* Put 'current' back into the tree. */
__enqueue_entity(cfs_rq, prev);
/* in !on_rq case, update occurred at dequeue */
- update_load_avg(prev, 0);
+ update_load_avg(cfs_rq, prev, 0);
}
cfs_rq->curr = NULL;
}
@@ -3997,8 +4280,8 @@ entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued)
/*
* Ensure that runnable average is periodically updated.
*/
- update_load_avg(curr, UPDATE_TG);
- update_cfs_shares(curr);
+ update_load_avg(cfs_rq, curr, UPDATE_TG);
+ update_cfs_group(curr);
#ifdef CONFIG_SCHED_HRTICK
/*
@@ -4915,8 +5198,8 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
if (cfs_rq_throttled(cfs_rq))
break;
- update_load_avg(se, UPDATE_TG);
- update_cfs_shares(se);
+ update_load_avg(cfs_rq, se, UPDATE_TG);
+ update_cfs_group(se);
}
if (!se)
@@ -4974,8 +5257,8 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
if (cfs_rq_throttled(cfs_rq))
break;
- update_load_avg(se, UPDATE_TG);
- update_cfs_shares(se);
+ update_load_avg(cfs_rq, se, UPDATE_TG);
+ update_cfs_group(se);
}
if (!se)
@@ -5449,6 +5732,8 @@ static unsigned long capacity_spare_wake(int cpu, struct task_struct *p)
/*
* find_idlest_group finds and returns the least busy CPU group within the
* domain.
+ *
+ * Assumes p is allowed on at least one CPU in sd.
*/
static struct sched_group *
find_idlest_group(struct sched_domain *sd, struct task_struct *p,
@@ -5456,8 +5741,9 @@ find_idlest_group(struct sched_domain *sd, struct task_struct *p,
{
struct sched_group *idlest = NULL, *group = sd->groups;
struct sched_group *most_spare_sg = NULL;
- unsigned long min_runnable_load = ULONG_MAX, this_runnable_load = 0;
- unsigned long min_avg_load = ULONG_MAX, this_avg_load = 0;
+ unsigned long min_runnable_load = ULONG_MAX;
+ unsigned long this_runnable_load = ULONG_MAX;
+ unsigned long min_avg_load = ULONG_MAX, this_avg_load = ULONG_MAX;
unsigned long most_spare = 0, this_spare = 0;
int load_idx = sd->forkexec_idx;
int imbalance_scale = 100 + (sd->imbalance_pct-100)/2;
@@ -5578,10 +5864,10 @@ skip_spare:
}
/*
- * find_idlest_cpu - find the idlest cpu among the cpus in group.
+ * find_idlest_group_cpu - find the idlest cpu among the cpus in group.
*/
static int
-find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
+find_idlest_group_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
{
unsigned long load, min_load = ULONG_MAX;
unsigned int min_exit_latency = UINT_MAX;
@@ -5630,6 +5916,53 @@ find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
return shallowest_idle_cpu != -1 ? shallowest_idle_cpu : least_loaded_cpu;
}
+static inline int find_idlest_cpu(struct sched_domain *sd, struct task_struct *p,
+ int cpu, int prev_cpu, int sd_flag)
+{
+ int new_cpu = cpu;
+
+ if (!cpumask_intersects(sched_domain_span(sd), &p->cpus_allowed))
+ return prev_cpu;
+
+ while (sd) {
+ struct sched_group *group;
+ struct sched_domain *tmp;
+ int weight;
+
+ if (!(sd->flags & sd_flag)) {
+ sd = sd->child;
+ continue;
+ }
+
+ group = find_idlest_group(sd, p, cpu, sd_flag);
+ if (!group) {
+ sd = sd->child;
+ continue;
+ }
+
+ new_cpu = find_idlest_group_cpu(group, p, cpu);
+ if (new_cpu == cpu) {
+ /* Now try balancing at a lower domain level of cpu */
+ sd = sd->child;
+ continue;
+ }
+
+ /* Now try balancing at a lower domain level of new_cpu */
+ cpu = new_cpu;
+ weight = sd->span_weight;
+ sd = NULL;
+ for_each_domain(cpu, tmp) {
+ if (weight <= tmp->span_weight)
+ break;
+ if (tmp->flags & sd_flag)
+ sd = tmp;
+ }
+ /* while loop will break here if sd == NULL */
+ }
+
+ return new_cpu;
+}
+
#ifdef CONFIG_SCHED_SMT
static inline void set_idle_cores(int cpu, int val)
@@ -5982,50 +6315,30 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_f
new_cpu = cpu;
}
+ if (sd && !(sd_flag & SD_BALANCE_FORK)) {
+ /*
+ * We're going to need the task's util for capacity_spare_wake
+ * in find_idlest_group. Sync it up to prev_cpu's
+ * last_update_time.
+ */
+ sync_entity_load_avg(&p->se);
+ }
+
if (!sd) {
- pick_cpu:
+pick_cpu:
if (sd_flag & SD_BALANCE_WAKE) /* XXX always ? */
new_cpu = select_idle_sibling(p, prev_cpu, new_cpu);
- } else while (sd) {
- struct sched_group *group;
- int weight;
-
- if (!(sd->flags & sd_flag)) {
- sd = sd->child;
- continue;
- }
-
- group = find_idlest_group(sd, p, cpu, sd_flag);
- if (!group) {
- sd = sd->child;
- continue;
- }
-
- new_cpu = find_idlest_cpu(group, p, cpu);
- if (new_cpu == -1 || new_cpu == cpu) {
- /* Now try balancing at a lower domain level of cpu */
- sd = sd->child;
- continue;
- }
-
- /* Now try balancing at a lower domain level of new_cpu */
- cpu = new_cpu;
- weight = sd->span_weight;
- sd = NULL;
- for_each_domain(cpu, tmp) {
- if (weight <= tmp->span_weight)
- break;
- if (tmp->flags & sd_flag)
- sd = tmp;
- }
- /* while loop will break here if sd == NULL */
+ } else {
+ new_cpu = find_idlest_cpu(sd, p, cpu, prev_cpu, sd_flag);
}
rcu_read_unlock();
return new_cpu;
}
+static void detach_entity_cfs_rq(struct sched_entity *se);
+
/*
* Called immediately before a task is migrated to a new cpu; task_cpu(p) and
* cfs_rq_of(p) references at time of call are still valid and identify the
@@ -6059,14 +6372,25 @@ static void migrate_task_rq_fair(struct task_struct *p)
se->vruntime -= min_vruntime;
}
- /*
- * We are supposed to update the task to "current" time, then its up to date
- * and ready to go to new CPU/cfs_rq. But we have difficulty in getting
- * what current time is, so simply throw away the out-of-date time. This
- * will result in the wakee task is less decayed, but giving the wakee more
- * load sounds not bad.
- */
- remove_entity_load_avg(&p->se);
+ if (p->on_rq == TASK_ON_RQ_MIGRATING) {
+ /*
+ * In case of TASK_ON_RQ_MIGRATING we in fact hold the 'old'
+ * rq->lock and can modify state directly.
+ */
+ lockdep_assert_held(&task_rq(p)->lock);
+ detach_entity_cfs_rq(&p->se);
+
+ } else {
+ /*
+ * We are supposed to update the task to "current" time, then
+ * its up to date and ready to go to new CPU/cfs_rq. But we
+ * have difficulty in getting what current time is, so simply
+ * throw away the out-of-date time. This will result in the
+ * wakee task is less decayed, but giving the wakee more load
+ * sounds not bad.
+ */
+ remove_entity_load_avg(&p->se);
+ }
/* Tell new CPU we are migrated */
p->se.avg.last_update_time = 0;
@@ -6334,10 +6658,7 @@ again:
set_next_entity(cfs_rq, se);
}
- if (hrtick_enabled(rq))
- hrtick_start_fair(rq, p);
-
- return p;
+ goto done;
simple:
#endif
@@ -6351,6 +6672,16 @@ simple:
p = task_of(se);
+done: __maybe_unused
+#ifdef CONFIG_SMP
+ /*
+ * Move the next running task to the front of
+ * the list, so our cfs_tasks list becomes MRU
+ * one.
+ */
+ list_move(&p->se.group_node, &rq->cfs_tasks);
+#endif
+
if (hrtick_enabled(rq))
hrtick_start_fair(rq, p);
@@ -6786,11 +7117,12 @@ static void detach_task(struct task_struct *p, struct lb_env *env)
*/
static struct task_struct *detach_one_task(struct lb_env *env)
{
- struct task_struct *p, *n;
+ struct task_struct *p;
lockdep_assert_held(&env->src_rq->lock);
- list_for_each_entry_safe(p, n, &env->src_rq->cfs_tasks, se.group_node) {
+ list_for_each_entry_reverse(p,
+ &env->src_rq->cfs_tasks, se.group_node) {
if (!can_migrate_task(p, env))
continue;
@@ -6836,7 +7168,7 @@ static int detach_tasks(struct lb_env *env)
if (env->idle != CPU_NOT_IDLE && env->src_rq->nr_running <= 1)
break;
- p = list_first_entry(tasks, struct task_struct, se.group_node);
+ p = list_last_entry(tasks, struct task_struct, se.group_node);
env->loop++;
/* We've more or less seen every task there is, call it quits */
@@ -6886,7 +7218,7 @@ static int detach_tasks(struct lb_env *env)
continue;
next:
- list_move_tail(&p->se.group_node, tasks);
+ list_move(&p->se.group_node, tasks);
}
/*
@@ -6962,7 +7294,7 @@ static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq)
if (cfs_rq->avg.util_sum)
return false;
- if (cfs_rq->runnable_load_sum)
+ if (cfs_rq->avg.runnable_load_sum)
return false;
return true;
@@ -6994,7 +7326,7 @@ static void update_blocked_averages(int cpu)
/* Propagate pending load changes to the parent, if any: */
se = cfs_rq->tg->se[cpu];
if (se && !skip_blocked_update(se))
- update_load_avg(se, 0);
+ update_load_avg(cfs_rq_of(se), se, 0);
/*
* There can be a lot of idle CPU cgroups. Don't let fully
@@ -7875,8 +8207,11 @@ static struct sched_group *find_busiest_group(struct lb_env *env)
if (busiest->group_type == group_imbalanced)
goto force_balance;
- /* SD_BALANCE_NEWIDLE trumps SMP nice when underutilized */
- if (env->idle == CPU_NEWLY_IDLE && group_has_capacity(env, local) &&
+ /*
+ * When dst_cpu is idle, prevent SMP nice and/or asymmetric group
+ * capacities from resulting in underutilization due to avg_load.
+ */
+ if (env->idle != CPU_NOT_IDLE && group_has_capacity(env, local) &&
busiest->group_no_capacity)
goto force_balance;
@@ -8693,7 +9028,7 @@ void nohz_balance_enter_idle(int cpu)
return;
/* Spare idle load balancing on CPUs that don't want to be disturbed: */
- if (!is_housekeeping_cpu(cpu))
+ if (!housekeeping_cpu(cpu, HK_FLAG_SCHED))
return;
if (test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))
@@ -9158,7 +9493,7 @@ static void propagate_entity_cfs_rq(struct sched_entity *se)
if (cfs_rq_throttled(cfs_rq))
break;
- update_load_avg(se, UPDATE_TG);
+ update_load_avg(cfs_rq, se, UPDATE_TG);
}
}
#else
@@ -9170,7 +9505,7 @@ static void detach_entity_cfs_rq(struct sched_entity *se)
struct cfs_rq *cfs_rq = cfs_rq_of(se);
/* Catch up with the cfs_rq and remove our load when we leave */
- update_load_avg(se, 0);
+ update_load_avg(cfs_rq, se, 0);
detach_entity_load_avg(cfs_rq, se);
update_tg_load_avg(cfs_rq, false);
propagate_entity_cfs_rq(se);
@@ -9189,7 +9524,7 @@ static void attach_entity_cfs_rq(struct sched_entity *se)
#endif
/* Synchronize entity with its cfs_rq */
- update_load_avg(se, sched_feat(ATTACH_AGE_LOAD) ? 0 : SKIP_AGE_LOAD);
+ update_load_avg(cfs_rq, se, sched_feat(ATTACH_AGE_LOAD) ? 0 : SKIP_AGE_LOAD);
attach_entity_load_avg(cfs_rq, se);
update_tg_load_avg(cfs_rq, false);
propagate_entity_cfs_rq(se);
@@ -9271,11 +9606,7 @@ void init_cfs_rq(struct cfs_rq *cfs_rq)
cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime;
#endif
#ifdef CONFIG_SMP
-#ifdef CONFIG_FAIR_GROUP_SCHED
- cfs_rq->propagate_avg = 0;
-#endif
- atomic_long_set(&cfs_rq->removed_load_avg, 0);
- atomic_long_set(&cfs_rq->removed_util_avg, 0);
+ raw_spin_lock_init(&cfs_rq->removed.lock);
#endif
}
@@ -9473,8 +9804,8 @@ int sched_group_set_shares(struct task_group *tg, unsigned long shares)
rq_lock_irqsave(rq, &rf);
update_rq_clock(rq);
for_each_sched_entity(se) {
- update_load_avg(se, UPDATE_TG);
- update_cfs_shares(se);
+ update_load_avg(cfs_rq_of(se), se, UPDATE_TG);
+ update_cfs_group(se);
}
rq_unlock_irqrestore(rq, &rf);
}
generated by cgit (git 2.34.1) at 2024-05-03 22:28:26 +0000