linux-kernel - [RFC PATCH V2 10/19] sched: detect wakeup burst with rq->avg

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Date:	Mon, 11 Aug 2014 17:07:31 +0530
From:	Preeti U Murthy <preeti@...ux.vnet.ibm.com>
To:	alex.shi@...el.com, vincent.guittot@...aro.org,
	peterz@...radead.org, pjt@...gle.com, efault@....de,
	rjw@...ysocki.net, morten.rasmussen@....com,
	svaidy@...ux.vnet.ibm.com, arjan@...ux.intel.com, mingo@...nel.org
Cc:	nicolas.pitre@...aro.org, len.brown@...el.com, yuyang.du@...el.com,
	linaro-kernel@...ts.linaro.org, daniel.lezcano@...aro.org,
	corbet@....net, catalin.marinas@....com, markgross@...gnar.org,
	sundar.iyer@...el.com, linux-kernel@...r.kernel.org,
	dietmar.eggemann@....com, Lorenzo.Pieralisi@....com,
	mike.turquette@...aro.org, akpm@...ux-foundation.org,
	paulmck@...ux.vnet.ibm.com, tglx@...utronix.de
Subject: [RFC PATCH V2 10/19] sched: detect wakeup burst with rq->avg_idle

From: Alex Shi <alex.shi@...el.com>

rq->avg_idle is 'to used to accommodate bursty loads in a dirt simple
dirt cheap manner' -- Mike Galbraith.

With this cheap and smart bursty indicator, we can find the wake up
burst, and just use nr_running as instant utilization only.

The 'sysctl_sched_burst_threshold' used for wakeup burst, set it as
double of sysctl_sched_migration_cost.

Signed-off-by: Alex Shi <alex.shi@...el.com>
[Added CONFIG_SCHED_POWER switch to enable this patch]
Signed-off-by: Preeti U Murthy <preeti@...ux.vnet.ibm.com>
---

 include/linux/sched/sysctl.h |    3 +++
 kernel/sched/fair.c          |    4 ++++
 kernel/sysctl.c              |    9 +++++++++
 3 files changed, 16 insertions(+)

diff --git a/include/linux/sched/sysctl.h b/include/linux/sched/sysctl.h
index 596a0e0..0a3307b 100644
--- a/include/linux/sched/sysctl.h
+++ b/include/linux/sched/sysctl.h
@@ -55,6 +55,9 @@ extern unsigned int sysctl_numa_balancing_scan_size;
 
 #ifdef CONFIG_SCHED_DEBUG
 extern unsigned int sysctl_sched_migration_cost;
+#ifdef CONFIG_SCHED_POWER
+extern unsigned int sysctl_sched_burst_threshold;
+#endif /* CONFIG_SCHED_POWER */
 extern unsigned int sysctl_sched_nr_migrate;
 extern unsigned int sysctl_sched_time_avg;
 extern unsigned int sysctl_timer_migration;
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 60abaf4..20e2414 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -92,6 +92,10 @@ unsigned int normalized_sysctl_sched_wakeup_granularity = 1000000UL;
 
 const_debug unsigned int sysctl_sched_migration_cost = 500000UL;
 
+#ifdef CONFIG_SCHED_POWER
+const_debug unsigned int sysctl_sched_burst_threshold = 1000000UL;
+#endif
+
 /*
  * The exponential sliding  window over which load is averaged for shares
  * distribution.
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 75875a7..8175d93 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -329,6 +329,15 @@ static struct ctl_table kern_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec,
 	},
+#ifdef CONFIG_SCHED_POWER
+	{
+		.procname	= "sched_burst_threshold_ns",
+		.data		= &sysctl_sched_burst_threshold,
+		.maxlen		= sizeof(unsigned int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+	},
+#endif /* CONFIG_SCHED_POWER */
 	{
 		.procname	= "sched_nr_migrate",
 		.data		= &sysctl_sched_nr_migrate,

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