Add new statistics which reflect the average time a task is running on the CPU
and the sum of these running time of the tasks on a runqueue. The latter is
named utilization_avg_contrib.
This patch is based on the usage metric that was proposed in the 1st
versions of the per-entity load tracking patchset by Paul Turner
<p...@google.com> but that has be removed afterward. This version differs
from the original one in the sense that it's not linked to task_group.
The rq's utilization_avg_contrib will be used to check if a rq is overloaded
or not instead of trying to compute how many task a group of CPUs can handle
Rename runnable_avg_period into avg_period as it is now used with both
runnable_avg_sum and running_avg_sum
Add some descriptions of the variables to explain their differences
Signed-off-by: Vincent Guittot <vincent.guit...@linaro.org>
---
include/linux/sched.h | 19 +++++++++++---
kernel/sched/debug.c | 9 ++++---
kernel/sched/fair.c | 68 +++++++++++++++++++++++++++++++++++++++------------
kernel/sched/sched.h | 8 +++++-
4 files changed, 81 insertions(+), 23 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 48ae6c4..51df220 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1071,15 +1071,26 @@ struct load_weight {
};
struct sched_avg {
+ u64 last_runnable_update;
+ s64 decay_count;
+ /*
+ * utilization_avg_contrib describes the amount of time that a
+ * sched_entity is running on a CPU. It is based on running_avg_sum
+ * and is scaled in the range [0..SCHED_LOAD_SCALE].
+ * load_avg_contrib described the the amount of time that a
+ * sched_entity is runnable on a rq. It is based on both
+ * runnable_avg_sum and the weight of the task.
+ */
+ unsigned long load_avg_contrib, utilization_avg_contrib;
/*
* These sums represent an infinite geometric series and so are bound
* above by 1024/(1-y). Thus we only need a u32 to store them for all
* choices of y < 1-2^(-32)*1024.
+ * runnable_avg_sum represents the amount of time a sched_entity is on
+ * the runqueue whereas running_avg_sum reflects the time the
+ * sched_entity is effectively running on the runqueue.
*/
- u32 runnable_avg_sum, runnable_avg_period;
- u64 last_runnable_update;
- s64 decay_count;
- unsigned long load_avg_contrib;
+ u32 runnable_avg_sum, avg_period, running_avg_sum;
};
#ifdef CONFIG_SCHEDSTATS
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index c7fe1ea0..1761db9 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -71,7 +71,7 @@ static void print_cfs_group_stats(struct seq_file *m, int
cpu, struct task_group
if (!se) {
struct sched_avg *avg = &cpu_rq(cpu)->avg;
P(avg->runnable_avg_sum);
- P(avg->runnable_avg_period);
+ P(avg->avg_period);
return;
}
@@ -94,7 +94,7 @@ static void print_cfs_group_stats(struct seq_file *m, int
cpu, struct task_group
P(se->load.weight);
#ifdef CONFIG_SMP
P(se->avg.runnable_avg_sum);
- P(se->avg.runnable_avg_period);
+ P(se->avg.avg_period);
P(se->avg.load_avg_contrib);
P(se->avg.decay_count);
#endif
@@ -215,6 +215,8 @@ void print_cfs_rq(struct seq_file *m, int cpu, struct
cfs_rq *cfs_rq)
cfs_rq->runnable_load_avg);
SEQ_printf(m, " .%-30s: %ld\n", "blocked_load_avg",
cfs_rq->blocked_load_avg);
+ SEQ_printf(m, " .%-30s: %ld\n", "utilization_load_avg",
+ cfs_rq->utilization_load_avg);
#ifdef CONFIG_FAIR_GROUP_SCHED
SEQ_printf(m, " .%-30s: %ld\n", "tg_load_contrib",
cfs_rq->tg_load_contrib);
@@ -631,7 +633,8 @@ void proc_sched_show_task(struct task_struct *p, struct
seq_file *m)
P(se.load.weight);
#ifdef CONFIG_SMP
P(se.avg.runnable_avg_sum);
- P(se.avg.runnable_avg_period);
+ P(se.avg.running_avg_sum);
+ P(se.avg.avg_period);
P(se.avg.load_avg_contrib);
P(se.avg.decay_count);
#endif
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 7422044..2cf153d 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -677,8 +677,8 @@ void init_task_runnable_average(struct task_struct *p)
p->se.avg.decay_count = 0;
slice = sched_slice(task_cfs_rq(p), &p->se) >> 10;
- p->se.avg.runnable_avg_sum = slice;
- p->se.avg.runnable_avg_period = slice;
+ p->se.avg.runnable_avg_sum = p->se.avg.running_avg_sum = slice;
+ p->se.avg.avg_period = slice;
__update_task_entity_contrib(&p->se);
}
#else
@@ -1547,7 +1547,7 @@ static u64 numa_get_avg_runtime(struct task_struct *p,
u64 *period)
*period = now - p->last_task_numa_placement;
} else {
delta = p->se.avg.runnable_avg_sum;
- *period = p->se.avg.runnable_avg_period;
+ *period = p->se.avg.avg_period;
}
p->last_sum_exec_runtime = runtime;
@@ -2297,7 +2297,8 @@ static u32 __compute_runnable_contrib(u64 n)
*/
static __always_inline int __update_entity_runnable_avg(u64 now,
struct sched_avg *sa,
- int runnable)
+ int runnable,
+ int running)
{
u64 delta, periods;
u32 runnable_contrib;
@@ -2323,7 +2324,7 @@ static __always_inline int
__update_entity_runnable_avg(u64 now,
sa->last_runnable_update = now;
/* delta_w is the amount already accumulated against our next period */
- delta_w = sa->runnable_avg_period % 1024;
+ delta_w = sa->avg_period % 1024;
if (delta + delta_w >= 1024) {
/* period roll-over */
decayed = 1;
@@ -2336,7 +2337,9 @@ static __always_inline int
__update_entity_runnable_avg(u64 now,
delta_w = 1024 - delta_w;
if (runnable)
sa->runnable_avg_sum += delta_w;
- sa->runnable_avg_period += delta_w;
+ if (running)
+ sa->running_avg_sum += delta_w;
+ sa->avg_period += delta_w;
delta -= delta_w;
@@ -2346,20 +2349,26 @@ static __always_inline int
__update_entity_runnable_avg(u64 now,
sa->runnable_avg_sum = decay_load(sa->runnable_avg_sum,
periods + 1);
- sa->runnable_avg_period = decay_load(sa->runnable_avg_period,
+ sa->running_avg_sum = decay_load(sa->running_avg_sum,
+ periods + 1);
+ sa->avg_period = decay_load(sa->avg_period,
periods + 1);
/* Efficiently calculate \sum (1..n_period) 1024*y^i */
runnable_contrib = __compute_runnable_contrib(periods);
if (runnable)
sa->runnable_avg_sum += runnable_contrib;
- sa->runnable_avg_period += runnable_contrib;
+ if (running)
+ sa->running_avg_sum += runnable_contrib;
+ sa->avg_period += runnable_contrib;
}
/* Remainder of delta accrued against u_0` */
if (runnable)
sa->runnable_avg_sum += delta;
- sa->runnable_avg_period += delta;
+ if (running)
+ sa->running_avg_sum += delta;
+ sa->avg_period += delta;
return decayed;
}
@@ -2411,7 +2420,7 @@ static inline void __update_tg_runnable_avg(struct
sched_avg *sa,
/* The fraction of a cpu used by this cfs_rq */
contrib = div_u64((u64)sa->runnable_avg_sum << NICE_0_SHIFT,
- sa->runnable_avg_period + 1);
+ sa->avg_period + 1);
contrib -= cfs_rq->tg_runnable_contrib;
if (abs(contrib) > cfs_rq->tg_runnable_contrib / 64) {
@@ -2464,7 +2473,8 @@ static inline void __update_group_entity_contrib(struct
sched_entity *se)
static inline void update_rq_runnable_avg(struct rq *rq, int runnable)
{
- __update_entity_runnable_avg(rq_clock_task(rq), &rq->avg, runnable);
+ __update_entity_runnable_avg(rq_clock_task(rq), &rq->avg, runnable,
+ runnable);
__update_tg_runnable_avg(&rq->avg, &rq->cfs);
}
#else /* CONFIG_FAIR_GROUP_SCHED */
@@ -2482,7 +2492,7 @@ static inline void __update_task_entity_contrib(struct
sched_entity *se)
/* avoid overflowing a 32-bit type w/ SCHED_LOAD_SCALE */
contrib = se->avg.runnable_avg_sum * scale_load_down(se->load.weight);
- contrib /= (se->avg.runnable_avg_period + 1);
+ contrib /= (se->avg.avg_period + 1);
se->avg.load_avg_contrib = scale_load(contrib);
}
@@ -2501,6 +2511,27 @@ static long __update_entity_load_avg_contrib(struct
sched_entity *se)
return se->avg.load_avg_contrib - old_contrib;
}
+
+static inline void __update_task_entity_utilization(struct sched_entity *se)
+{
+ u32 contrib;
+
+ /* avoid overflowing a 32-bit type w/ SCHED_LOAD_SCALE */
+ contrib = se->avg.running_avg_sum * scale_load_down(SCHED_LOAD_SCALE);
+ contrib /= (se->avg.avg_period + 1);
+ se->avg.utilization_avg_contrib = scale_load(contrib);
+}
+
+static long __update_entity_utilization_avg_contrib(struct sched_entity *se)
+{
+ long old_contrib = se->avg.utilization_avg_contrib;
+
+ if (entity_is_task(se))
+ __update_task_entity_utilization(se);
+
+ return se->avg.utilization_avg_contrib - old_contrib;
+}
+
static inline void subtract_blocked_load_contrib(struct cfs_rq *cfs_rq,
long load_contrib)
{
@@ -2517,7 +2548,7 @@ static inline void update_entity_load_avg(struct
sched_entity *se,
int update_cfs_rq)
{
struct cfs_rq *cfs_rq = cfs_rq_of(se);
- long contrib_delta;
+ long contrib_delta, utilization_delta;
u64 now;
/*
@@ -2529,16 +2560,20 @@ static inline void update_entity_load_avg(struct
sched_entity *se,
else
now = cfs_rq_clock_task(group_cfs_rq(se));
- if (!__update_entity_runnable_avg(now, &se->avg, se->on_rq))
+ if (!__update_entity_runnable_avg(now, &se->avg, se->on_rq,
+ cfs_rq->curr == se))
return;
contrib_delta = __update_entity_load_avg_contrib(se);
+ utilization_delta = __update_entity_utilization_avg_contrib(se);
if (!update_cfs_rq)
return;
- if (se->on_rq)
+ if (se->on_rq) {
cfs_rq->runnable_load_avg += contrib_delta;
+ cfs_rq->utilization_load_avg += utilization_delta;
+ }
else
subtract_blocked_load_contrib(cfs_rq, -contrib_delta);
}
@@ -2615,6 +2650,7 @@ static inline void enqueue_entity_load_avg(struct cfs_rq
*cfs_rq,
}
cfs_rq->runnable_load_avg += se->avg.load_avg_contrib;
+ cfs_rq->utilization_load_avg += se->avg.utilization_avg_contrib;
/* we force update consideration on load-balancer moves */
update_cfs_rq_blocked_load(cfs_rq, !wakeup);
}
@@ -2633,6 +2669,7 @@ static inline void dequeue_entity_load_avg(struct cfs_rq
*cfs_rq,
update_cfs_rq_blocked_load(cfs_rq, !sleep);
cfs_rq->runnable_load_avg -= se->avg.load_avg_contrib;
+ cfs_rq->utilization_load_avg -= se->avg.utilization_avg_contrib;
if (sleep) {
cfs_rq->blocked_load_avg += se->avg.load_avg_contrib;
se->avg.decay_count = atomic64_read(&cfs_rq->decay_counter);
@@ -2970,6 +3007,7 @@ 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_entity_load_avg(se, 1);
}
update_stats_curr_start(cfs_rq, se);
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index f332e45..3ccb136 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -339,8 +339,14 @@ struct cfs_rq {
* Under CFS, load is tracked on a per-entity basis and aggregated up.
* This allows for the description of both thread and group usage (in
* the FAIR_GROUP_SCHED case).
+ * runnable_load_avg is the sum of the load_avg_contrib of the
+ * sched_entities on the rq.
+ * blocked_load_avg is similar to runnable_load_avg except that its
+ * the blocked sched_entities on the rq.
+ * utilization_load_avg is the sum of the average running time of the
+ * sched_entities on the rq.
*/
- unsigned long runnable_load_avg, blocked_load_avg;
+ unsigned long runnable_load_avg, blocked_load_avg, utilization_load_avg;
atomic64_t decay_counter;
u64 last_decay;
atomic_long_t removed_load;
--
1.9.1
--
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