rq_stats: Doing rq_stats calculation in the scheduler tick.
With this change, we do the average run queue statistics calculation
in the scheduler tick itself. This helps avoid any extra timers to
do the same. Also doing this calculation in the scheduler tick avoids
any bias if the calculation is done in a workqueue
Change-Id: I854d90acc05cc7a7226487be5555976826d8c837
Signed-off-by: Amar Singhal <asinghal@codeaurora.org>
diff --git a/include/linux/rq_stats.h b/include/linux/rq_stats.h
new file mode 100644
index 0000000..e04063f
--- /dev/null
+++ b/include/linux/rq_stats.h
@@ -0,0 +1,31 @@
+/* Copyright (c) 2011, Code Aurora Forum. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ */
+
+struct rq_data {
+ unsigned int rq_avg;
+ unsigned long rq_poll_jiffies;
+ unsigned long def_timer_jiffies;
+ unsigned long rq_poll_last_jiffy;
+ unsigned long rq_poll_total_jiffies;
+ unsigned long def_timer_last_jiffy;
+ unsigned int def_interval;
+ int64_t def_start_time;
+ struct attribute_group *attr_group;
+ struct kobject *kobj;
+ struct work_struct def_timer_work;
+ int init;
+};
+
+extern spinlock_t rq_lock;
+extern struct rq_data rq_info;
+extern struct workqueue_struct *rq_wq;
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index d5097c4..2480d18 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -20,11 +20,17 @@
#include <linux/profile.h>
#include <linux/sched.h>
#include <linux/module.h>
+#include <linux/rq_stats.h>
#include <asm/irq_regs.h>
#include "tick-internal.h"
+
+struct rq_data rq_info;
+struct workqueue_struct *rq_wq;
+spinlock_t rq_lock;
+
/*
* Per cpu nohz control structure
*/
@@ -711,6 +717,50 @@
* High resolution timer specific code
*/
#ifdef CONFIG_HIGH_RES_TIMERS
+static void update_rq_stats(void)
+{
+ unsigned long jiffy_gap = 0;
+ unsigned int rq_avg = 0;
+ unsigned long flags = 0;
+
+ jiffy_gap = jiffies - rq_info.rq_poll_last_jiffy;
+
+ if (jiffy_gap >= rq_info.rq_poll_jiffies) {
+
+ spin_lock_irqsave(&rq_lock, flags);
+
+ if (!rq_info.rq_avg)
+ rq_info.rq_poll_total_jiffies = 0;
+
+ rq_avg = nr_running() * 10;
+
+ if (rq_info.rq_poll_total_jiffies) {
+ rq_avg = (rq_avg * jiffy_gap) +
+ (rq_info.rq_avg *
+ rq_info.rq_poll_total_jiffies);
+ do_div(rq_avg,
+ rq_info.rq_poll_total_jiffies + jiffy_gap);
+ }
+
+ rq_info.rq_avg = rq_avg;
+ rq_info.rq_poll_total_jiffies += jiffy_gap;
+ rq_info.rq_poll_last_jiffy = jiffies;
+
+ spin_unlock_irqrestore(&rq_lock, flags);
+ }
+}
+
+static void wakeup_user(void)
+{
+ unsigned long jiffy_gap;
+
+ jiffy_gap = jiffies - rq_info.def_timer_last_jiffy;
+
+ if (jiffy_gap >= rq_info.def_timer_jiffies) {
+ rq_info.def_timer_last_jiffy = jiffies;
+ queue_work(rq_wq, &rq_info.def_timer_work);
+ }
+}
/*
* We rearm the timer until we get disabled by the idle code.
* Called with interrupts disabled and timer->base->cpu_base->lock held.
@@ -758,6 +808,20 @@
}
update_process_times(user_mode(regs));
profile_tick(CPU_PROFILING);
+
+
+ if ((rq_info.init == 1) && (cpu == 0)) {
+
+ /*
+ * update run queue statistics
+ */
+ update_rq_stats();
+
+ /*
+ * wakeup user if needed
+ */
+ wakeup_user();
+ }
}
hrtimer_forward(timer, now, tick_period);