[RFC PATCH 09/16] sched, cpufreq: Introduce current cpu compute capacity into scheduler

From: Morten Rasmussen
Date: Fri May 23 2014 - 14:19:21 EST


The scheduler is currently unaware of frequency changes and the current
compute capacity offered by the cpus. This patch is not the solution.
It is a hack to give us something to experiment with for now.

A proper solution could be based on the frequency invariant load
tracking proposed in the past: https://lkml.org/lkml/2013/4/16/289

This patch should _not_ be considered safe.

Signed-off-by: Morten Rasmussen <morten.rasmussen@xxxxxxx>
---
drivers/cpufreq/cpufreq.c | 2 ++
include/linux/sched.h | 2 ++
kernel/sched/fair.c | 6 ++++++
kernel/sched/sched.h | 2 ++
4 files changed, 12 insertions(+)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index abda660..a2b788d 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -28,6 +28,7 @@
#include <linux/slab.h>
#include <linux/suspend.h>
#include <linux/tick.h>
+#include <linux/sched.h>
#include <trace/events/power.h>

/**
@@ -315,6 +316,7 @@ static void __cpufreq_notify_transition(struct cpufreq_policy *policy,
pr_debug("FREQ: %lu - CPU: %lu\n",
(unsigned long)freqs->new, (unsigned long)freqs->cpu);
trace_cpu_frequency(freqs->new, freqs->cpu);
+ set_curr_capacity(freqs->cpu, (freqs->new*1024)/policy->max);
srcu_notifier_call_chain(&cpufreq_transition_notifier_list,
CPUFREQ_POSTCHANGE, freqs);
if (likely(policy) && likely(policy->cpu == freqs->cpu))
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 62d61b5..727b936 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -3068,4 +3068,6 @@ static inline unsigned long rlimit_max(unsigned int limit)
return task_rlimit_max(current, limit);
}

+void set_curr_capacity(int cpu, long capacity);
+
#endif
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 7570dd9..3a2aeee 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -7410,9 +7410,15 @@ void init_cfs_rq(struct cfs_rq *cfs_rq)
#ifdef CONFIG_SMP
atomic64_set(&cfs_rq->decay_counter, 1);
atomic_long_set(&cfs_rq->removed_load, 0);
+ atomic_long_set(&cfs_rq->curr_capacity, 1024);
#endif
}

+void set_curr_capacity(int cpu, long capacity)
+{
+ atomic_long_set(&cpu_rq(cpu)->cfs.curr_capacity, capacity);
+}
+
#ifdef CONFIG_FAIR_GROUP_SCHED
static void task_move_group_fair(struct task_struct *p, int on_rq)
{
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 9ff67a7..5a117b8 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -341,6 +341,8 @@ struct cfs_rq {
u64 last_decay;
atomic_long_t removed_load;

+ atomic_long_t curr_capacity;
+
#ifdef CONFIG_FAIR_GROUP_SCHED
/* Required to track per-cpu representation of a task_group */
u32 tg_runnable_contrib;
--
1.7.9.5


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