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Date: Tue, 16 Apr 2013 16:26:35 +0100
From: Chris Redpath <chris.redpath@....com>
To: linux-kernel@...r.kernel.org
Cc: Paul Turner <pjt@...gle.com>,
Peter Zijlstra <peterz@...radead.org>,
Alex Shi <alex.shi@...el.com>,
Viresh Kumar <viresh.kumar@...aro.org>,
"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
Ingo Molnar <mingo@...hat.com>,
"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
Morten Rasmussen <morten.rasmussen@....com>,
Vincent Guittot <vincent.guittot@...aro.org>,
Preeti U Murthy <preeti@...ux.vnet.ibm.com>,
Todd Poynor <toddpoynor@...gle.com>
Subject: [RFC PATCH 3/3] sched: Scale load contribution by CPU Capacity
Modulate the tracked load of a task using the measure of current
and maximum compute capacity for the core it is executing on.
Change-Id: If6aea806e631f2313fd925c8902260a522663dbd
Conflicts:
kernel/sched/fair.c
---
kernel/sched/fair.c | 51 +++++++++++++++++++++++++++++++++++++++++++--------
1 file changed, 43 insertions(+), 8 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index f6bbe1e..3f3ee08 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1319,11 +1319,15 @@ static inline void update_cpu_capacity(int cpu)
static __always_inline int __update_entity_runnable_avg(u64 now,
struct sched_avg *sa,
int runnable,
- int running)
+ int running,
+ int cpu)
{
u64 delta, periods;
u32 runnable_contrib;
int delta_w, decayed = 0;
+#ifdef CONFIG_ARCH_SCALE_INVARIANT_CPU_CAPACITY
+ u32 curr_scale = 1<<SCHED_ARCH_SCALE_POWER_SHIFT;
+#endif /* CONFIG_ARCH_SCALE_INVARIANT_CPU_CAPACITY */
delta = now - sa->last_runnable_update;
/*
@@ -1344,6 +1348,12 @@ static __always_inline int __update_entity_runnable_avg(u64 now,
return 0;
sa->last_runnable_update = now;
+#ifdef CONFIG_ARCH_SCALE_INVARIANT_CPU_CAPACITY
+ update_cpu_capacity(cpu);
+ curr_scale = (compute_capacity_of(cpu) << SCHED_ARCH_SCALE_POWER_SHIFT)
+ / (max_compute_capacity_of(cpu)+1);
+#endif
+
/* delta_w is the amount already accumulated against our next period */
delta_w = sa->runnable_avg_period % 1024;
if (delta + delta_w >= 1024) {
@@ -1356,13 +1366,17 @@ static __always_inline int __update_entity_runnable_avg(u64 now,
* period and accrue it.
*/
delta_w = 1024 - delta_w;
+ sa->runnable_avg_period += delta_w;
+ delta -= delta_w;
+ /* scale runnable time if necessary */
+#ifdef CONFIG_ARCH_SCALE_INVARIANT_CPU_CAPACITY
+ delta_w = (delta_w * curr_scale)
+ >> SCHED_ARCH_SCALE_POWER_SHIFT;
+#endif
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;
/* Figure out how many additional periods this update spans */
periods = delta / 1024;
@@ -1376,19 +1390,31 @@ static __always_inline int __update_entity_runnable_avg(u64 now,
/* Efficiently calculate \sum (1..n_period) 1024*y^i */
runnable_contrib = __compute_runnable_contrib(periods);
+ sa->runnable_avg_period += runnable_contrib;
+ /* Apply load scaling if necessary.
+ * Note that multiplying the whole series is same as
+ * multiplying all terms
+ */
+#ifdef CONFIG_ARCH_SCALE_INVARIANT_CPU_CAPACITY
+ runnable_contrib = (runnable_contrib * curr_scale)
+ >> SCHED_ARCH_SCALE_POWER_SHIFT;
+#endif
if (runnable)
sa->runnable_avg_sum += runnable_contrib;
if (running)
sa->usage_avg_sum += runnable_contrib;
- sa->runnable_avg_period += runnable_contrib;
}
/* Remainder of delta accrued against u_0` */
+ sa->runnable_avg_period += delta;
+ /* scale if necessary */
+#ifdef CONFIG_ARCH_SCALE_INVARIANT_CPU_CAPACITY
+ delta = ((delta * curr_scale) >> SCHED_ARCH_SCALE_POWER_SHIFT);
+#endif
if (runnable)
sa->runnable_avg_sum += delta;
if (running)
sa->usage_avg_sum += delta;
- sa->runnable_avg_period += delta;
return decayed;
}
@@ -1551,7 +1577,11 @@ static inline void update_entity_load_avg(struct sched_entity *se,
struct cfs_rq *cfs_rq = cfs_rq_of(se);
long contrib_delta;
u64 now;
+ int cpu = -1; /* not used in normal case */
+#ifdef CONFIG_ARCH_SCALE_INVARIANT_CPU_CAPACITY
+ cpu = cfs_rq->rq->cpu;
+#endif
/*
* For a group entity we need to use their owned cfs_rq_clock_task() in
* case they are the parent of a throttled hierarchy.
@@ -1562,7 +1592,7 @@ static inline void update_entity_load_avg(struct sched_entity *se,
now = cfs_rq_clock_task(group_cfs_rq(se));
if (!__update_entity_runnable_avg(now, &se->avg, se->on_rq,
- cfs_rq->curr == se))
+ cfs_rq->curr == se, cpu))
return;
contrib_delta = __update_entity_load_avg_contrib(se);
@@ -1607,8 +1637,13 @@ 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)
{
u32 contrib;
+ int cpu = -1; /* not used in normal case */
+
+#ifdef CONFIG_ARCH_SCALE_INVARIANT_CPU_CAPACITY
+ cpu = rq->cpu;
+#endif
__update_entity_runnable_avg(rq->clock_task, &rq->avg, runnable,
- runnable);
+ runnable, cpu);
__update_tg_runnable_avg(&rq->avg, &rq->cfs);
contrib = rq->avg.runnable_avg_sum * scale_load_down(1024);
contrib /= (rq->avg.runnable_avg_period + 1);
--
1.7.9.5
--
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