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/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);