[PATCH] O1int 0307021808 for interactivity

Con Kolivas (kernel@kolivas.org)
Wed, 2 Jul 2003 18:23:56 +1000


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This latest patch I'm formally announcing has the base O1int changes so far
but includes new semantics for freshly started applications so they can
become interactive very rapidly even during heavy load. This addresses the
"slow to start new apps" evident in O1int so far.

Please test this one and note given just how rapidly things can become
interactive it may have regressions in other settings.

This performs better in all settings than any previous one I've posted in my
testing, but hardware differs substantially!

The latest should always be found:
http://kernel.kolivas.org/2.5

Con

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--- linux-2.5.73/include/linux/sched.h 2003-06-30 10:06:40.000000000 +1000
+++ linux-2.5.73-test/include/linux/sched.h 2003-07-01 11:56:08.000000000 +1000
@@ -336,6 +336,7 @@ struct task_struct {
prio_array_t *array;

unsigned long sleep_avg;
+ unsigned long avg_start;
unsigned long last_run;

unsigned long policy;
--- linux-2.5.73/kernel/sched.c 2003-06-30 10:06:40.000000000 +1000
+++ linux-2.5.73-test/kernel/sched.c 2003-07-02 17:57:04.000000000 +1000
@@ -72,6 +72,7 @@
#define EXIT_WEIGHT 3
#define PRIO_BONUS_RATIO 25
#define INTERACTIVE_DELTA 2
+#define MIN_SLEEP_AVG (HZ)
#define MAX_SLEEP_AVG (10*HZ)
#define STARVATION_LIMIT (10*HZ)
#define NODE_THRESHOLD 125
@@ -297,6 +298,21 @@ static inline void enqueue_task(struct t
p->array = array;
}

+static inline void normalise_sleep(task_t *p)
+{
+ int old_avg_time, new_avg_time;
+ new_avg_time = MIN_SLEEP_AVG;
+ old_avg_time = jiffies - p->avg_start;
+ if (old_avg_time < new_avg_time) return;
+
+ if (p->sleep_avg > MAX_SLEEP_AVG)
+ p->sleep_avg = MAX_SLEEP_AVG;
+ if (old_avg_time > MAX_SLEEP_AVG)
+ old_avg_time = MAX_SLEEP_AVG;
+ p->sleep_avg = p->sleep_avg * new_avg_time / old_avg_time;
+ p->avg_start = jiffies - new_avg_time;
+}
+
/*
* effective_prio - return the priority that is based on the static
* priority but is modified by bonuses/penalties.
@@ -314,11 +330,23 @@ static inline void enqueue_task(struct t
static int effective_prio(task_t *p)
{
int bonus, prio;
+ long sleep_period;

if (rt_task(p))
return p->prio;

- bonus = MAX_USER_PRIO*PRIO_BONUS_RATIO*p->sleep_avg/MAX_SLEEP_AVG/100 -
+ sleep_period = jiffies - p->avg_start;
+
+ if (!sleep_period)
+ return p->static_prio;
+
+ if (sleep_period > MAX_SLEEP_AVG)
+ sleep_period = MAX_SLEEP_AVG;
+
+ if (p->sleep_avg > sleep_period)
+ sleep_period = p->sleep_avg;
+
+ bonus = MAX_USER_PRIO*PRIO_BONUS_RATIO*p->sleep_avg/sleep_period/100 -
MAX_USER_PRIO*PRIO_BONUS_RATIO/100/2;

prio = p->static_prio - bonus;
@@ -349,7 +377,7 @@ static inline void activate_task(task_t
long sleep_time = jiffies - p->last_run - 1;

if (sleep_time > 0) {
- int sleep_avg;
+ int runtime = jiffies - p->avg_start;

/*
* This code gives a bonus to interactive tasks.
@@ -359,7 +387,10 @@ static inline void activate_task(task_t
* spends sleeping, the higher the average gets - and the
* higher the priority boost gets as well.
*/
- sleep_avg = p->sleep_avg + sleep_time;
+ p->sleep_avg += sleep_time;
+ if (runtime < MAX_SLEEP_AVG)
+ p->sleep_avg += (runtime - p->sleep_avg) * (MAX_SLEEP_AVG - runtime)/MAX_SLEEP_AVG;
+

/*
* 'Overflow' bonus ticks go to the waker as well, so the
@@ -367,12 +398,17 @@ static inline void activate_task(task_t
* boosting tasks that are related to maximum-interactive
* tasks.
*/
- if (sleep_avg > MAX_SLEEP_AVG)
- sleep_avg = MAX_SLEEP_AVG;
- if (p->sleep_avg != sleep_avg) {
- p->sleep_avg = sleep_avg;
- p->prio = effective_prio(p);
+ if (p->sleep_avg > MAX_SLEEP_AVG * 12/10)
+ p->sleep_avg = MAX_SLEEP_AVG * 11/10;
+ if (sleep_time > MIN_SLEEP_AVG){
+ p->avg_start = jiffies - MIN_SLEEP_AVG;
+ p->sleep_avg = MIN_SLEEP_AVG / 2;
}
+ if (unlikely(p->avg_start > jiffies)){
+ p->avg_start = jiffies;
+ p->sleep_avg = 0;
+ }
+ p->prio = effective_prio(p);
}
__activate_task(p, rq);
}
@@ -550,6 +586,8 @@ void wake_up_forked_process(task_t * p)
* from forking tasks that are max-interactive.
*/
current->sleep_avg = current->sleep_avg * PARENT_PENALTY / 100;
+ p->avg_start = current->avg_start;
+ normalise_sleep(p);
p->sleep_avg = p->sleep_avg * CHILD_PENALTY / 100;
p->prio = effective_prio(p);
set_task_cpu(p, smp_processor_id());

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