[PATCH 5/7] sched: Implement usage tracking

From: Morten Rasmussen
Date: Mon Sep 22 2014 - 12:24:46 EST


With the framework for runnable tracking now fully in place, per-entity
usage tracking is a simple and low-overhead addition.

This is a rebased and significantly cut down version of a patch
originally authored by Paul Turner <pjt@xxxxxxxxxx>.

cc: Paul Turner <pjt@xxxxxxxxxx>
cc: Ben Segall <bsegall@xxxxxxxxxx>

Signed-off-by: Morten Rasmussen <morten.rasmussen@xxxxxxx>
---
include/linux/sched.h | 1 +
kernel/sched/debug.c | 1 +
kernel/sched/fair.c | 16 +++++++++++++---
3 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 18f5262..0bcd8a7 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1080,6 +1080,7 @@ struct sched_avg {
u64 last_runnable_update;
s64 decay_count;
unsigned long load_avg_contrib;
+ u32 usage_avg_sum;
};

#ifdef CONFIG_SCHEDSTATS
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index c7fe1ea0..ed5a9ce 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -95,6 +95,7 @@ static void print_cfs_group_stats(struct seq_file *m, int cpu, struct task_group
#ifdef CONFIG_SMP
P(se->avg.runnable_avg_sum);
P(se->avg.runnable_avg_period);
+ P(se->avg.usage_avg_sum);
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 52abb3e..d8a8c83 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2299,7 +2299,8 @@ unsigned long arch_scale_load_capacity(int cpu);
*/
static __always_inline int __update_entity_runnable_avg(u64 now, int cpu,
struct sched_avg *sa,
- int runnable)
+ int runnable,
+ int running)
{
u64 delta, periods;
u32 runnable_contrib;
@@ -2341,6 +2342,8 @@ static __always_inline int __update_entity_runnable_avg(u64 now, int cpu,
if (runnable)
sa->runnable_avg_sum += (delta_w * scale_cap)
>> SCHED_CAPACITY_SHIFT;
+ if (running)
+ sa->usage_avg_sum += delta_w;
sa->runnable_avg_period += delta_w;

delta -= delta_w;
@@ -2353,6 +2356,7 @@ static __always_inline int __update_entity_runnable_avg(u64 now, int cpu,
periods + 1);
sa->runnable_avg_period = decay_load(sa->runnable_avg_period,
periods + 1);
+ sa->usage_avg_sum = decay_load(sa->usage_avg_sum, periods + 1);

/* Efficiently calculate \sum (1..n_period) 1024*y^i */
runnable_contrib = __compute_runnable_contrib(periods);
@@ -2360,6 +2364,8 @@ static __always_inline int __update_entity_runnable_avg(u64 now, int cpu,
if (runnable)
sa->runnable_avg_sum += (runnable_contrib * scale_cap)
>> SCHED_CAPACITY_SHIFT;
+ if (running)
+ sa->usage_avg_sum += runnable_contrib;
sa->runnable_avg_period += runnable_contrib;
}

@@ -2367,6 +2373,8 @@ static __always_inline int __update_entity_runnable_avg(u64 now, int cpu,
if (runnable)
sa->runnable_avg_sum += (delta * scale_cap)
>> SCHED_CAPACITY_SHIFT;
+ if (running)
+ sa->usage_avg_sum += delta;
sa->runnable_avg_period += delta;

return decayed;
@@ -2473,7 +2481,7 @@ 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->cpu, &rq->avg,
- runnable);
+ runnable, runnable);
__update_tg_runnable_avg(&rq->avg, &rq->cfs);
}
#else /* CONFIG_FAIR_GROUP_SCHED */
@@ -2539,7 +2547,8 @@ 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, cpu, &se->avg, se->on_rq))
+ if (!__update_entity_runnable_avg(now, cpu, &se->avg, se->on_rq,
+ cfs_rq->curr == se))
return;

contrib_delta = __update_entity_load_avg_contrib(se);
@@ -2980,6 +2989,7 @@ 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);
--
1.7.9.5


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