linux-kernel - [RFC][PATCH 4/7] sched: power: Remove power capacity hints for kworker threads

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Date:	Fri, 11 Oct 2013 18:19:14 +0100
From:	Morten Rasmussen <morten.rasmussen@....com>
To:	mingo@...nel.org, peterz@...radead.org
Cc:	pjt@...gle.com, arjan@...ux.intel.com, rjw@...k.pl,
	dirk.j.brandewie@...el.com, vincent.guittot@...aro.org,
	alex.shi@...aro.org, preeti@...ux.vnet.ibm.com, efault@....de,
	corbet@....net, tglx@...utronix.de, catalin.marinas@....com,
	morten.rasmussen@....com, linux-kernel@...r.kernel.org,
	linaro-kernel@...ts.linaro.org
Subject: [RFC][PATCH 4/7] sched: power: Remove power capacity hints for kworker threads

Removing power hints for kworker threads enables easier use of
workqueues in the power driver late callback. That would otherwise
lead to an endless loop unless it is prevented in the power driver.

Signed-off-by: Morten Rasmussen <morten.rasmussen@....com>
---
 kernel/sched/fair.c |   20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 50ae0ce..ea8d973 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2856,23 +2856,29 @@ static inline void hrtick_update(struct rq *rq)
 static unsigned long weighted_cpuload(const int cpu);
 static unsigned long power_of(int cpu);
 
-static inline void inc_cpu_capacity(int cpu)
+static inline void inc_cpu_capacity(int cpu, struct task_struct *p)
 {
+	if (p && p->flags & PF_WQ_WORKER)
+		return;
+
 	if (weighted_cpuload(cpu) > power_of(cpu))
 		go_faster(cpu, 0);
 }
 
-static inline void dec_cpu_capacity(int cpu)
+static inline void dec_cpu_capacity(int cpu, struct task_struct *p)
 {
+	if (p && p->flags & PF_WQ_WORKER)
+		return;
+
 	if (weighted_cpuload(cpu) < power_of(cpu))
 		go_slower(cpu, 0);
 }
 #else
-static inline void inc_cpu_capacity(int cpu)
+static inline void inc_cpu_capacity(int cpu, struct task_struct *p)
 {
 }
 
-static inline void dec_cpu_capacity(int cpu)
+static inline void dec_cpu_capacity(int cpu, struct task_struct *p)
 {
 }
 #endif
@@ -2923,7 +2929,7 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
 		inc_nr_running(rq);
 	}
 
-	inc_cpu_capacity(task_cpu(p));
+	inc_cpu_capacity(task_cpu(p), p);
 	hrtick_update(rq);
 }
 
@@ -2986,7 +2992,7 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
 		update_rq_runnable_avg(rq, 1);
 	}
 
-	dec_cpu_capacity(task_cpu(p));
+	dec_cpu_capacity(task_cpu(p), p);
 	hrtick_update(rq);
 }
 
@@ -5772,7 +5778,7 @@ static void run_rebalance_domains(struct softirq_action *h)
 	 */
 	nohz_idle_balance(this_cpu, idle);
 
-	inc_cpu_capacity(this_cpu);
+	inc_cpu_capacity(this_cpu, NULL);
 	power_late_callback(this_cpu);
 }
 
-- 
1.7.9.5


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