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Subject[tip:sched/core] sched/fair: Consolidate nohz CPU load update code
Commit-ID:  be68a682c00dfa7733021e1da386ba7182fc7bb9
Gitweb: http://git.kernel.org/tip/be68a682c00dfa7733021e1da386ba7182fc7bb9
Author: Frederic Weisbecker <fweisbec@gmail.com>
AuthorDate: Wed, 13 Jan 2016 17:01:29 +0100
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Mon, 29 Feb 2016 09:53:04 +0100

sched/fair: Consolidate nohz CPU load update code

Lets factorize a bit of code there. We'll even have a third user soon.
While at it, standardize the idle update function name against the
others.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Byungchul Park <byungchul.park@lge.com>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E . McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1452700891-21807-3-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
kernel/sched/fair.c | 48 +++++++++++++++++++++++++-----------------------
1 file changed, 25 insertions(+), 23 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 3b3dc39..3313052 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4542,6 +4542,25 @@ static unsigned long weighted_cpuload(const int cpu)
}

#ifdef CONFIG_NO_HZ_COMMON
+static void __update_cpu_load_nohz(struct rq *this_rq,
+ unsigned long curr_jiffies,
+ unsigned long load,
+ int active)
+{
+ unsigned long pending_updates;
+
+ pending_updates = curr_jiffies - this_rq->last_load_update_tick;
+ if (pending_updates) {
+ this_rq->last_load_update_tick = curr_jiffies;
+ /*
+ * In the regular NOHZ case, we were idle, this means load 0.
+ * In the NOHZ_FULL case, we were non-idle, we should consider
+ * its weighted load.
+ */
+ __update_cpu_load(this_rq, load, pending_updates, active);
+ }
+}
+
/*
* There is no sane way to deal with nohz on smp when using jiffies because the
* cpu doing the jiffies update might drift wrt the cpu doing the jiffy reading
@@ -4559,22 +4578,15 @@ static unsigned long weighted_cpuload(const int cpu)
* Called from nohz_idle_balance() to update the load ratings before doing the
* idle balance.
*/
-static void update_idle_cpu_load(struct rq *this_rq)
+static void update_cpu_load_idle(struct rq *this_rq)
{
- unsigned long curr_jiffies = READ_ONCE(jiffies);
- unsigned long load = weighted_cpuload(cpu_of(this_rq));
- unsigned long pending_updates;
-
/*
* bail if there's load or we're actually up-to-date.
*/
- if (load || curr_jiffies == this_rq->last_load_update_tick)
+ if (weighted_cpuload(cpu_of(this_rq)))
return;

- pending_updates = curr_jiffies - this_rq->last_load_update_tick;
- this_rq->last_load_update_tick = curr_jiffies;
-
- __update_cpu_load(this_rq, load, pending_updates, 0);
+ __update_cpu_load_nohz(this_rq, READ_ONCE(jiffies), 0, 0);
}

/*
@@ -4585,22 +4597,12 @@ void update_cpu_load_nohz(int active)
struct rq *this_rq = this_rq();
unsigned long curr_jiffies = READ_ONCE(jiffies);
unsigned long load = active ? weighted_cpuload(cpu_of(this_rq)) : 0;
- unsigned long pending_updates;

if (curr_jiffies == this_rq->last_load_update_tick)
return;

raw_spin_lock(&this_rq->lock);
- pending_updates = curr_jiffies - this_rq->last_load_update_tick;
- if (pending_updates) {
- this_rq->last_load_update_tick = curr_jiffies;
- /*
- * In the regular NOHZ case, we were idle, this means load 0.
- * In the NOHZ_FULL case, we were non-idle, we should consider
- * its weighted load.
- */
- __update_cpu_load(this_rq, load, pending_updates, active);
- }
+ __update_cpu_load_nohz(this_rq, curr_jiffies, load, active);
raw_spin_unlock(&this_rq->lock);
}
#endif /* CONFIG_NO_HZ */
@@ -4612,7 +4614,7 @@ void update_cpu_load_active(struct rq *this_rq)
{
unsigned long load = weighted_cpuload(cpu_of(this_rq));
/*
- * See the mess around update_idle_cpu_load() / update_cpu_load_nohz().
+ * See the mess around update_cpu_load_idle() / update_cpu_load_nohz().
*/
this_rq->last_load_update_tick = jiffies;
__update_cpu_load(this_rq, load, 1, 1);
@@ -7906,7 +7908,7 @@ static void nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle)
if (time_after_eq(jiffies, rq->next_balance)) {
raw_spin_lock_irq(&rq->lock);
update_rq_clock(rq);
- update_idle_cpu_load(rq);
+ update_cpu_load_idle(rq);
raw_spin_unlock_irq(&rq->lock);
rebalance_domains(rq, CPU_IDLE);
}
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