Add new statistics which reflect the average time a task is running on the
CPU and the sum of the tasks' running on a runqueue. The latter is named
usage_avg_contrib.
This patch is based on the usage metric that was proposed in the 1st
versions of the per-entity load tracking patchset 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 usage_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
Signed-off-by: Vincent Guittot <vincent.guit...@linaro.org>
---
include/linux/sched.h | 4 ++--
kernel/sched/fair.c | 47 ++++++++++++++++++++++++++++++++++++++++++-----
kernel/sched/sched.h | 2 +-
3 files changed, 45 insertions(+), 8 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 5c2c885..7dfd584 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1073,10 +1073,10 @@ struct sched_avg {
* above by 1024/(1-y). Thus we only need a u32 to store them for all
* choices of y < 1-2^(-32)*1024.
*/
- u32 runnable_avg_sum, runnable_avg_period;
+ u32 runnable_avg_sum, runnable_avg_period, running_avg_sum;
u64 last_runnable_update;
s64 decay_count;
- unsigned long load_avg_contrib;
+ unsigned long load_avg_contrib, usage_avg_contrib;
};
#ifdef CONFIG_SCHEDSTATS
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 60ae1ce..1fd2131 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -676,7 +676,7 @@ 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_sum = p->se.avg.running_avg_sum = slice;
p->se.avg.runnable_avg_period = slice;
__update_task_entity_contrib(&p->se);
}
@@ -2289,7 +2289,8 @@ 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;
@@ -2328,6 +2329,8 @@ static __always_inline int
__update_entity_runnable_avg(u64 now,
delta_w = 1024 - delta_w;
if (runnable)
sa->runnable_avg_sum += delta_w;
+ if (running)
+ sa->running_avg_sum += delta_w;
sa->runnable_avg_period += delta_w;
delta -= delta_w;
@@ -2338,6 +2341,8 @@ static __always_inline int
__update_entity_runnable_avg(u64 now,
sa->runnable_avg_sum = decay_load(sa->runnable_avg_sum,
periods + 1);
+ sa->running_avg_sum = decay_load(sa->running_avg_sum,
+ periods + 1);
sa->runnable_avg_period = decay_load(sa->runnable_avg_period,
periods + 1);
@@ -2345,12 +2350,16 @@ static __always_inline int
__update_entity_runnable_avg(u64 now,
runnable_contrib = __compute_runnable_contrib(periods);
if (runnable)
sa->runnable_avg_sum += runnable_contrib;
+ if (running)
+ sa->running_avg_sum += runnable_contrib;
sa->runnable_avg_period += runnable_contrib;
}
/* Remainder of delta accrued against u_0` */
if (runnable)
sa->runnable_avg_sum += delta;
+ if (running)
+ sa->running_avg_sum += delta;
sa->runnable_avg_period += delta;
return decayed;
@@ -2490,6 +2499,27 @@ 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_usage(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.runnable_avg_period + 1);
+ se->avg.usage_avg_contrib = scale_load(contrib);
+}
+
+static long __update_entity_usage_avg_contrib(struct sched_entity *se)
+{
+ long old_contrib = se->avg.usage_avg_contrib;
+
+ if (entity_is_task(se))
+ __update_task_entity_usage(se);
+
+ return se->avg.usage_avg_contrib - old_contrib;
+}
+
static inline void subtract_blocked_load_contrib(struct cfs_rq *cfs_rq,
long load_contrib)
{
@@ -2506,7 +2536,7 @@ 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, usage_delta;
u64 now;
/*
@@ -2518,16 +2548,20 @@ 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);
+ usage_delta = __update_entity_usage_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->usage_load_avg += usage_delta;
+ }
else
subtract_blocked_load_contrib(cfs_rq, -contrib_delta);
}
@@ -2604,6 +2638,7 @@ static inline void enqueue_entity_load_avg(struct cfs_rq
*cfs_rq,
}
cfs_rq->runnable_load_avg += se->avg.load_avg_contrib;
+ cfs_rq->usage_load_avg += se->avg.usage_avg_contrib;
/* we force update consideration on load-balancer moves */
update_cfs_rq_blocked_load(cfs_rq, !wakeup);
}
@@ -2622,6 +2657,7 @@ 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->usage_load_avg -= se->avg.usage_avg_contrib;
if (sleep) {
cfs_rq->blocked_load_avg += se->avg.load_avg_contrib;
se->avg.decay_count = atomic64_read(&cfs_rq->decay_counter);
@@ -2959,6 +2995,7 @@ 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 7c0a74e..d625fbb 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -340,7 +340,7 @@ struct cfs_rq {
* This allows for the description of both thread and group usage (in
* the FAIR_GROUP_SCHED case).
*/
- unsigned long runnable_load_avg, blocked_load_avg;
+ unsigned long runnable_load_avg, blocked_load_avg, usage_load_avg;
atomic64_t decay_counter;
u64 last_decay;
atomic_long_t removed_load;
--
1.9.1
--
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