linux-kernel - [patch v7 11/21] sched: add sched_burst_threshold

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Date:	Thu,  4 Apr 2013 10:00:52 +0800
From:	Alex Shi <alex.shi@...el.com>
To:	mingo@...hat.com, peterz@...radead.org, tglx@...utronix.de,
	akpm@...ux-foundation.org, arjan@...ux.intel.com, bp@...en8.de,
	pjt@...gle.com, namhyung@...nel.org, efault@....de,
	morten.rasmussen@....com
Cc:	vincent.guittot@...aro.org, gregkh@...uxfoundation.org,
	preeti@...ux.vnet.ibm.com, viresh.kumar@...aro.org,
	linux-kernel@...r.kernel.org, alex.shi@...el.com,
	len.brown@...el.com, rafael.j.wysocki@...el.com, jkosina@...e.cz,
	clark.williams@...il.com, tony.luck@...el.com,
	keescook@...omium.org, mgorman@...e.de, riel@...hat.com
Subject: [patch v7 11/21] sched: add sched_burst_threshold_ns as wakeup burst indicator

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, since we will
check every cpu's avg_idle, the value get be more precise, set 0.1ms.

Signed-off-by: Alex Shi <alex.shi@...el.com>
---
 include/linux/sched/sysctl.h | 1 +
 kernel/sched/fair.c          | 1 +
 kernel/sysctl.c              | 7 +++++++
 3 files changed, 9 insertions(+)

diff --git a/include/linux/sched/sysctl.h b/include/linux/sched/sysctl.h
index bf8086b..a3c3d43 100644
--- a/include/linux/sched/sysctl.h
+++ b/include/linux/sched/sysctl.h
@@ -53,6 +53,7 @@ extern unsigned int sysctl_numa_balancing_settle_count;
 
 #ifdef CONFIG_SCHED_DEBUG
 extern unsigned int sysctl_sched_migration_cost;
+extern unsigned int sysctl_sched_burst_threshold;
 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 0c08773..f610313 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -91,6 +91,7 @@ unsigned int sysctl_sched_wakeup_granularity = 1000000UL;
 unsigned int normalized_sysctl_sched_wakeup_granularity = 1000000UL;
 
 const_debug unsigned int sysctl_sched_migration_cost = 500000UL;
+const_debug unsigned int sysctl_sched_burst_threshold = 100000UL;
 
 /*
  * The exponential sliding  window over which load is averaged for shares
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index afc1dc6..1f23457 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -327,6 +327,13 @@ static struct ctl_table kern_table[] = {
 		.proc_handler	= proc_dointvec,
 	},
 	{
+		.procname	= "sched_burst_threshold_ns",
+		.data		= &sysctl_sched_burst_threshold,
+		.maxlen		= sizeof(unsigned int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+	},
+	{
 		.procname	= "sched_nr_migrate",
 		.data		= &sysctl_sched_nr_migrate,
 		.maxlen		= sizeof(unsigned int),
-- 
1.7.12

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