[PATCH 3/4] sched: clean up cpu_load update

From: Alex Shi
Date: Tue Dec 03 2013 - 04:08:13 EST


Since we don't decay the rq->cpu_load, so we don't need the
pending_updates. But we still want update rq->rt_avg, so
still keep rq->last_load_update_tick and func __update_cpu_load.

After remove the load_idx, in the most of time the source_load is
equal to target_load, except only when source cpu is idle. At that
time we force set the cpu_load is 0(in update_cpu_load_nohz).
So we still left cpu_load in rq.

Signed-off-by: Alex Shi <alex.shi@xxxxxxxxxx>
---
kernel/sched/proc.c | 11 ++++-------
1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/kernel/sched/proc.c b/kernel/sched/proc.c
index a2435c5..057bb9b 100644
--- a/kernel/sched/proc.c
+++ b/kernel/sched/proc.c
@@ -404,8 +404,7 @@ static void calc_load_account_active(struct rq *this_rq)
* scheduler tick (TICK_NSEC). With tickless idle this will not be called
* every tick. We fix it up based on jiffies.
*/
-static void __update_cpu_load(struct rq *this_rq, unsigned long this_load,
- unsigned long pending_updates)
+static void __update_cpu_load(struct rq *this_rq, unsigned long this_load)
{
this_rq->nr_load_updates++;

@@ -449,7 +448,6 @@ void update_idle_cpu_load(struct rq *this_rq)
{
unsigned long curr_jiffies = ACCESS_ONCE(jiffies);
unsigned long load = get_rq_runnable_load(this_rq);
- unsigned long pending_updates;

/*
* bail if there's load or we're actually up-to-date.
@@ -457,10 +455,9 @@ void update_idle_cpu_load(struct rq *this_rq)
if (load || curr_jiffies == this_rq->last_load_update_tick)
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);
+ __update_cpu_load(this_rq, load);
}

/*
@@ -483,7 +480,7 @@ void update_cpu_load_nohz(void)
* We were idle, this means load 0, the current load might be
* !0 due to remote wakeups and the sort.
*/
- __update_cpu_load(this_rq, 0, pending_updates);
+ __update_cpu_load(this_rq, 0);
}
raw_spin_unlock(&this_rq->lock);
}
@@ -499,7 +496,7 @@ void update_cpu_load_active(struct rq *this_rq)
* See the mess around update_idle_cpu_load() / update_cpu_load_nohz().
*/
this_rq->last_load_update_tick = jiffies;
- __update_cpu_load(this_rq, load, 1);
+ __update_cpu_load(this_rq, load);

calc_load_account_active(this_rq);
}
--
1.8.1.2

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