[RFC PATCH 14/14] sched: implement usage tracking

From: Paul Turner
Date: Wed Feb 01 2012 - 20:45:06 EST


With the frame-work for runnable tracking now fully in place. Per-entity usage
tracking is a simple and low-overhead addition.

Signed-off-by: Paul Turner <pjt@xxxxxxxxxx>
Signed-off-by: Ben Segall <bsegall@xxxxxxxxxx>
---
include/linux/sched.h | 1 +
kernel/sched/debug.c | 3 +++
kernel/sched/fair.c | 29 +++++++++++++++++++++++------
kernel/sched/sched.h | 4 ++--
4 files changed, 29 insertions(+), 8 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 09b8c45..209185f 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1159,6 +1159,7 @@ struct load_weight {
struct sched_avg {
u64 runnable_avg_sum, runnable_avg_period;
u64 last_runnable_update, decay_count;
+ u32 usage_avg_sum;
unsigned long load_avg_contrib;

int contributes_blocked_load;
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index 0911ec6..4d39069 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -93,6 +93,7 @@ static void print_cfs_group_stats(struct seq_file *m, int cpu, struct task_group
P(se->load.weight);
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);
#undef PN
@@ -228,6 +229,8 @@ void print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq)
cfs_rq->tg_runnable_contrib);
SEQ_printf(m, " .%-30s: %d\n", "tg->runnable_avg",
atomic_read(&cfs_rq->tg->runnable_avg));
+ SEQ_printf(m, " .%-30s: %d\n", "tg->usage_avg",
+ atomic_read(&cfs_rq->tg->usage_avg));
#endif

print_cfs_group_stats(m, cpu, cfs_rq->tg);
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index ad524bb..222c2c9 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -997,7 +997,8 @@ static u32 __compute_runnable_contrib(int n)
*/
static __always_inline int __update_entity_runnable_avg(u64 now,
struct sched_avg *sa,
- int runnable)
+ int runnable,
+ int running)
{
u64 delta;
u32 periods, runnable_contrib;
@@ -1026,6 +1027,8 @@ 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->usage_avg_sum += delta_w;
sa->runnable_avg_period += delta_w;

delta -= delta_w;
@@ -1036,15 +1039,20 @@ static __always_inline int __update_entity_runnable_avg(u64 now,
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);

runnable_contrib = __compute_runnable_contrib(periods);
if (runnable)
sa->runnable_avg_sum += runnable_contrib;
+ if (running)
+ sa->usage_avg_sum += runnable_contrib;
sa->runnable_avg_period += runnable_contrib;
}

if (runnable)
sa->runnable_avg_sum += delta;
+ if (running)
+ sa->usage_avg_sum += delta;
sa->runnable_avg_period += delta;

return decayed;
@@ -1081,14 +1089,21 @@ static inline void __update_tg_runnable_avg(struct sched_avg *sa,
struct cfs_rq *cfs_rq)
{
struct task_group *tg = cfs_rq->tg;
- long contrib;
+ long contrib, usage_contrib;

contrib = (sa->runnable_avg_sum << 12) / (sa->runnable_avg_period + 1);
contrib -= cfs_rq->tg_runnable_contrib;

- if (abs(contrib) > cfs_rq->tg_runnable_contrib/64) {
+ usage_contrib = (sa->usage_avg_sum << 12) / (sa->runnable_avg_period + 1);
+ usage_contrib -= cfs_rq->tg_usage_contrib;
+
+ if ((abs(contrib) > cfs_rq->tg_runnable_contrib/64) ||
+ (abs(usage_contrib) > cfs_rq->tg_usage_contrib/64)) {
atomic_add(contrib, &tg->runnable_avg);
cfs_rq->tg_runnable_contrib += contrib;
+
+ atomic_add(usage_contrib, &tg->usage_avg);
+ cfs_rq->tg_usage_contrib += usage_contrib;
}
}

@@ -1164,8 +1179,8 @@ static inline void update_entity_load_avg(struct sched_entity *se,
struct cfs_rq *cfs_rq = cfs_rq_of(se);
long contrib_delta;

- if(!__update_entity_runnable_avg(rq_of(cfs_rq)->clock_task, &se->avg,
- se->on_rq))
+ if(!__update_entity_runnable_avg(cfs_rq_clock_task(cfs_rq), &se->avg,
+ se->on_rq, cfs_rq->curr == se))
return;

contrib_delta = __update_entity_load_avg_contrib(se);
@@ -1210,7 +1225,8 @@ static void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq, int force_update)

static inline void update_rq_runnable_avg(struct rq *rq, int runnable)
{
- __update_entity_runnable_avg(rq->clock_task, &rq->avg, runnable);
+ __update_entity_runnable_avg(rq->clock_task, &rq->avg, runnable,
+ runnable);
__update_tg_runnable_avg(&rq->avg, &rq->cfs);
}

@@ -1590,6 +1606,7 @@ 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 77f3297..9602a47 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -117,7 +117,7 @@ struct task_group {

atomic_t load_weight;
atomic64_t load_avg;
- atomic_t runnable_avg;
+ atomic_t runnable_avg, usage_avg;
#endif

#ifdef CONFIG_RT_GROUP_SCHED
@@ -260,7 +260,7 @@ struct cfs_rq {
*/
unsigned long h_load;

- u32 tg_runnable_contrib;
+ u32 tg_runnable_contrib, tg_usage_contrib;
u64 runnable_load_avg, blocked_load_avg;
u64 tg_load_contrib;
atomic64_t decay_counter, removed_load;


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