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Message-Id: <1406800573-9692-1-git-send-email-vincent.guittot@linaro.org>
Date: Thu, 31 Jul 2014 11:56:13 +0200
From: Vincent Guittot <vincent.guittot@...aro.org>
To: yuyang.du@...el.com, peterz@...radead.org
Cc: mingo@...hat.com, linux-kernel@...r.kernel.org, pjt@...gle.com,
bsegall@...gle.com, arjan.van.de.ven@...el.com,
len.brown@...el.com, rafael.j.wysocki@...el.com,
alan.cox@...el.com, mark.gross@...el.com, fengguang.wu@...el.com,
morten.rasmussen@....com,
Vincent Guittot <vincent.guittot@...aro.org>
Subject: Re: [PATCH 2/2 v4] sched: Rewrite per entity runnable load average
Resend with a correct subject
Hi Yuyang,
Does something like the patch below to be applied of top of your patchset, seem
reasonable add-on?
It adds 1 new usage_sum statistics which is something that I use to detect the
overload of a rq in my patchset that reworks cpu_power and removes
capacity_factor
And I think that the change I made on load_sum should match some of Morten's
concerns
Regards,
Vincent
---
Subject: [PATCH] sched: add usage_sum statistic
Add a new statitic that reflects the average time a task is running on CPU.
load_sum is now the average runnable time before being weighted
The sum of usage_sum of the tasks that are on a rq, is used to detect
the overload of a rq.
Signed-off-by: Vincent Guittot <vincent.guittot@...aro.org>
---
include/linux/sched.h | 1 +
kernel/sched/fair.c | 47 +++++++++++++++++++++++++++++++++++------------
kernel/sched/sched.h | 2 ++
3 files changed, 38 insertions(+), 12 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index b6617a1..3296e76 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1080,6 +1080,7 @@ struct sched_avg {
*/
u64 last_update_time;
u64 load_sum;
+ unsigned long usage_sum;
unsigned long load_avg;
u32 period_contrib;
};
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index a3a3168..78408a0 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -679,7 +679,8 @@ void init_task_runnable_average(struct task_struct *p)
*/
sa->period_contrib = 1023;
sa->load_avg = p->se.load.weight;
- sa->load_sum = p->se.load.weight * LOAD_AVG_MAX;
+ sa->load_sum = sa->usage_sum = LOAD_AVG_MAX;
+ ;
/* when this task enqueue'ed, it will contribute to its cfs_rq's load_avg */
}
#else
@@ -2300,7 +2301,7 @@ static u32 __compute_runnable_contrib(u64 n)
* = 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, struct sched_avg *sa, unsigned long w)
+__update_load_avg(u64 now, struct sched_avg *sa, unsigned long w, int running)
{
u64 delta, periods;
u32 contrib;
@@ -2340,7 +2341,9 @@ __update_load_avg(u64 now, struct sched_avg *sa, unsigned long w)
*/
delta_w = 1024 - delta_w;
if (w)
- sa->load_sum += w * delta_w;
+ sa->load_sum += delta_w;
+ if (running)
+ sa->usage_sum += delta_w;
delta -= delta_w;
@@ -2349,21 +2352,26 @@ __update_load_avg(u64 now, struct sched_avg *sa, unsigned long w)
delta %= 1024;
sa->load_sum = decay_load(sa->load_sum, periods + 1);
+ sa->usage_sum = decay_load(sa->usage_sum, periods + 1);
/* Efficiently calculate \sum (1..n_period) 1024*y^i */
contrib = __compute_runnable_contrib(periods);
if (w)
- sa->load_sum += w * contrib;
+ sa->load_sum += contrib;
+ if (running)
+ sa->usage_sum += contrib;
}
/* Remainder of delta accrued against u_0` */
if (w)
- sa->load_sum += w * delta;
+ sa->load_sum += delta;
+ if (running)
+ sa->usage_sum += delta;
sa->period_contrib += delta;
if (decayed)
- sa->load_avg = div_u64(sa->load_sum, LOAD_AVG_MAX);
+ sa->load_avg = div_u64(sa->load_sum * w, LOAD_AVG_MAX);
return decayed;
}
@@ -2404,11 +2412,17 @@ static inline int update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq)
if (atomic_long_read(&cfs_rq->removed_load_avg)) {
long r = atomic_long_xchg(&cfs_rq->removed_load_avg, 0);
cfs_rq->avg.load_avg = subtract_until_zero(cfs_rq->avg.load_avg, r);
- r *= LOAD_AVG_MAX;
+ }
+ if (atomic_long_read(&cfs_rq->removed_load_sum)) {
+ long r = atomic_long_xchg(&cfs_rq->removed_load_sum, 0);
cfs_rq->avg.load_sum = subtract_until_zero(cfs_rq->avg.load_sum, r);
}
+ if (atomic_long_read(&cfs_rq->removed_usage_sum)) {
+ long r = atomic_long_xchg(&cfs_rq->removed_usage_sum, 0);
+ cfs_rq->avg.usage_sum = subtract_until_zero(cfs_rq->avg.usage_sum, r);
+ }
- decayed = __update_load_avg(now, &cfs_rq->avg, cfs_rq->load.weight);
+ decayed = __update_load_avg(now, &cfs_rq->avg, cfs_rq->load.weight, cfs_rq->curr != NULL);
#ifndef CONFIG_64BIT
if (cfs_rq->avg.last_update_time != cfs_rq->load_last_update_time_copy) {
@@ -2430,7 +2444,8 @@ static inline void update_load_avg(struct sched_entity *se, int update_tg)
* Track task load average for carrying it to new CPU after migrated,
* and group sched_entity for task_h_load calc in migration
*/
- __update_load_avg(now, &se->avg, se->on_rq * se->load.weight);
+ __update_load_avg(now, &se->avg, se->on_rq * se->load.weight,
+ entity_is_task(se) ? task_of(se)->on_cpu : 0);
if (update_cfs_rq_load_avg(now, cfs_rq) && update_tg)
update_tg_load_avg(cfs_rq);
@@ -2451,13 +2466,14 @@ static inline void enqueue_entity_load_avg(struct sched_entity *se)
migrated = 1;
}
else
- __update_load_avg(now, sa, se->on_rq * se->load.weight);
+ __update_load_avg(now, sa, se->on_rq * se->load.weight, entity_is_task(se) ? task_of(se)->on_cpu : 0);
decayed = update_cfs_rq_load_avg(now, cfs_rq);
if (migrated) {
cfs_rq->avg.load_avg += sa->load_avg;
cfs_rq->avg.load_sum += sa->load_sum;
+ cfs_rq->avg.usage_sum += sa->usage_sum;
}
if (decayed || migrated)
@@ -4442,8 +4458,10 @@ migrate_task_rq_fair(struct task_struct *p, int next_cpu)
#else
last_update_time = cfs_rq->avg.last_update_time;
#endif
- __update_load_avg(last_update_time, &se->avg, 0);
+ __update_load_avg(last_update_time, &se->avg, 0, p->on_cpu);
atomic_long_add(se->avg.load_avg, &cfs_rq->removed_load_avg);
+ atomic_long_add(se->avg.load_sum, &cfs_rq->removed_load_sum);
+ atomic_long_add(se->avg.usage_sum, &cfs_rq->removed_usage_sum);
/*
* We are supposed to update the task to "current" time, then its up to date
@@ -7316,11 +7334,13 @@ static void switched_from_fair(struct rq *rq, struct task_struct *p)
* Remove our load from contribution when we leave cfs_rq.
*/
__update_load_avg(cfs_rq->avg.last_update_time, &se->avg,
- se->on_rq * se->load.weight);
+ se->on_rq * se->load.weight, p->on_cpu);
cfs_rq->avg.load_avg =
subtract_until_zero(cfs_rq->avg.load_avg, se->avg.load_avg);
cfs_rq->avg.load_sum =
subtract_until_zero(cfs_rq->avg.load_sum, se->avg.load_sum);
+ cfs_rq->avg.usage_sum =
+ subtract_until_zero(cfs_rq->avg.usage_sum, se->avg.usage_sum);
#endif
}
@@ -7378,6 +7398,8 @@ void init_cfs_rq(struct cfs_rq *cfs_rq)
#endif
#ifdef CONFIG_SMP
atomic_long_set(&cfs_rq->removed_load_avg, 0);
+ atomic_long_set(&cfs_rq->removed_load_sum, 0);
+ atomic_long_set(&cfs_rq->removed_usage_sum, 0);
#endif
}
@@ -7428,6 +7450,7 @@ static void task_move_group_fair(struct task_struct *p, int on_rq)
p->se.avg.last_update_time = cfs_rq->avg.last_update_time;
cfs_rq->avg.load_avg += p->se.avg.load_avg;
cfs_rq->avg.load_sum += p->se.avg.load_sum;
+ cfs_rq->avg.usage_sum += p->se.avg.usage_sum;
#endif
}
}
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index f21ddde..1bdd878 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -335,6 +335,8 @@ struct cfs_rq {
struct sched_avg avg;
unsigned long tg_load_avg_contrib;
atomic_long_t removed_load_avg;
+ atomic_long_t removed_load_sum;
+ atomic_long_t removed_usage_sum;
#ifndef CONFIG_64BIT
u64 load_last_update_time_copy;
#endif
--
1.9.1
--
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