[PATCH 1/5] sched-cleanup_task_activated.patch

[PATCH 1/5] sched-cleanup_task_activated.patch

[Con Kolivas]

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The activated flag in task_struct is used to track different sleep types
and its usage is somewhat obfuscated. Convert the variable to an enum with
more descriptive names without altering the function.

Signed-off-by: Con Kolivas <kernel@kolivas.org>

 include/linux/sched.h |    9 ++++++++-
 kernel/sched.c        |   24 +++++++++++++++---------
 2 files changed, 23 insertions(+), 10 deletions(-)

Index: linux-2.6.15/include/linux/sched.h
===================================================================
--- linux-2.6.15.orig/include/linux/sched.h
+++ linux-2.6.15/include/linux/sched.h
@@ -683,6 +683,13 @@ static inline void prefetch_stack(struct
 struct audit_context;		/* See audit.c */
 struct mempolicy;
 
+enum sleep_type {
+	SLEEP_NORMAL,
+	SLEEP_NONINTERACTIVE,
+	SLEEP_INTERACTIVE,
+	SLEEP_INTERRUPTED,
+};
+
 struct task_struct {
 	volatile long state;	/* -1 unrunnable, 0 runnable, >0 stopped */
 	struct thread_info *thread_info;
@@ -704,7 +711,7 @@ struct task_struct {
 	unsigned long sleep_avg;
 	unsigned long long timestamp, last_ran;
 	unsigned long long sched_time; /* sched_clock time spent running */
-	int activated;
+	enum sleep_type sleep_type;
 
 	unsigned long policy;
 	cpumask_t cpus_allowed;
Index: linux-2.6.15/kernel/sched.c
===================================================================
--- linux-2.6.15.orig/kernel/sched.c
+++ linux-2.6.15/kernel/sched.c
@@ -751,7 +751,7 @@ static int recalc_task_prio(task_t *p, u
 		 * prevent them suddenly becoming cpu hogs and starving
 		 * other processes.
 		 */
-		if (p->mm && p->activated != -1 &&
+		if (p->mm && p->sleep_type != SLEEP_NONINTERACTIVE &&
 			sleep_time > INTERACTIVE_SLEEP(p)) {
 				p->sleep_avg = JIFFIES_TO_NS(MAX_SLEEP_AVG -
 						DEF_TIMESLICE);
@@ -767,7 +767,7 @@ static int recalc_task_prio(task_t *p, u
 			 * limited in their sleep_avg rise as they
 			 * are likely to be waiting on I/O
 			 */
-			if (p->activated == -1 && p->mm) {
+			if (p->sleep_type == SLEEP_NONINTERACTIVE && p->mm) {
 				if (p->sleep_avg >= INTERACTIVE_SLEEP(p))
 					sleep_time = 0;
 				else if (p->sleep_avg + sleep_time >=
@@ -822,7 +822,7 @@ static void activate_task(task_t *p, run
 	 * This checks to make sure it's not an uninterruptible task
 	 * that is now waking up.
 	 */
-	if (!p->activated) {
+	if (p->sleep_type == SLEEP_NORMAL) {
 		/*
 		 * Tasks which were woken up by interrupts (ie. hw events)
 		 * are most likely of interactive nature. So we give them
@@ -831,13 +831,13 @@ static void activate_task(task_t *p, run
 		 * on a CPU, first time around:
 		 */
 		if (in_interrupt())
-			p->activated = 2;
+			p->sleep_type = SLEEP_INTERRUPTED;
 		else {
 			/*
 			 * Normal first-time wakeups get a credit too for
 			 * on-runqueue time, but it will be weighted down:
 			 */
-			p->activated = 1;
+			p->sleep_type = SLEEP_INTERACTIVE;
 		}
 	}
 	p->timestamp = now;
@@ -1359,7 +1359,7 @@ out_activate:
 		 * Tasks on involuntary sleep don't earn
 		 * sleep_avg beyond just interactive state.
 		 */
-		p->activated = -1;
+		p->sleep_type = SLEEP_NONINTERACTIVE;
 	}
 
 	/*
@@ -2938,6 +2938,12 @@ EXPORT_SYMBOL(sub_preempt_count);
 
 #endif
 
+static inline int interactive_sleep(enum sleep_type sleep_type)
+{
+	return (sleep_type == SLEEP_INTERACTIVE ||
+		sleep_type == SLEEP_INTERRUPTED);
+}
+
 /*
  * schedule() is the main scheduler function.
  */
@@ -3063,12 +3069,12 @@ go_idle:
 	queue = array->queue + idx;
 	next = list_entry(queue->next, task_t, run_list);
 
-	if (!rt_task(next) && next->activated > 0) {
+	if (!rt_task(next) && interactive_sleep(next->sleep_type)) {
 		unsigned long long delta = now - next->timestamp;
 		if (unlikely((long long)(now - next->timestamp) < 0))
 			delta = 0;
 
-		if (next->activated == 1)
+		if (next->sleep_type == SLEEP_INTERACTIVE)
 			delta = delta * (ON_RUNQUEUE_WEIGHT * 128 / 100) / 128;
 
 		array = next->array;
@@ -3081,7 +3087,7 @@ go_idle:
 		} else
 			requeue_task(next, array);
 	}
-	next->activated = 0;
+	next->sleep_type = SLEEP_NORMAL;
 switch_tasks:
 	if (next == rq->idle)
 		schedstat_inc(rq, sched_goidle);

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Re: [PATCH 1/5] sched-cleanup_task_activated.patch

[Andrew Morton]

Con Kolivas <kernel@kolivas.org> wrote:
>
> +enum sleep_type {
> +	SLEEP_NORMAL,
> +	SLEEP_NONINTERACTIVE,
> +	SLEEP_INTERACTIVE,
> +	SLEEP_INTERRUPTED,
> +};

If you make these 1, 2, 4 and 8

> +static inline int interactive_sleep(enum sleep_type sleep_type)
> +{
> +	return (sleep_type == SLEEP_INTERACTIVE ||
> +		sleep_type == SLEEP_INTERRUPTED);
> +}

then this can be

	return sleep_type & (SLEEP_INTERACTIVE|SLEEP_INTERRUPTED);

which would save, oh, about nothing.

Re: [PATCH 1/5] sched-cleanup_task_activated.patch

[Con Kolivas]

On Friday 13 January 2006 21:28, Andrew Morton wrote:
> Con Kolivas <kernel@kolivas.org> wrote:
> > +enum sleep_type {
> > +	SLEEP_NORMAL,
> > +	SLEEP_NONINTERACTIVE,
> > +	SLEEP_INTERACTIVE,
> > +	SLEEP_INTERRUPTED,
> > +};
>
> If you make these 1, 2, 4 and 8
>
> > +static inline int interactive_sleep(enum sleep_type sleep_type)
> > +{
> > +	return (sleep_type == SLEEP_INTERACTIVE ||
> > +		sleep_type == SLEEP_INTERRUPTED);
> > +}
>
> then this can be
>
> 	return sleep_type & (SLEEP_INTERACTIVE|SLEEP_INTERRUPTED);
>
> which would save, oh, about nothing.

Hah yeah I went for readability over one cycle. Change it if you care; I don't 
mind :).

Cheers,
Con