Re: [PATCH] O6int for interactivity

Wiktor Wodecki
2003-07-16T21:45:27Z

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Hello,

I have been gone from the computer for a couple of hours, and now
everything is very chopping. For example I'm transfering some huge data
over nfs to another linux box (on sun, tho) where there is not enough
space available. It happens that in the middle of the copying the
process 'hangs'. I cannot interrupt it with ctrl-[cz], it takes a couple
of seconds (~20). I cannot tell for sure that the problem is with the O6
patch, since I haven't done it on an other kernel, yet.

On Thu, Jul 17, 2003 at 12:30:25AM +1000, Con Kolivas wrote:
> O*int patches trying to improve the interactivity of the 2.5/6 scheduler for
> desktops. It appears possible to do this without moving to nanosecond
> resolution.
>
> This one makes a massive difference... Please test this to death.
>
> Changes:
> The big change is in the way sleep_avg is incremented. Any amount of sleep
> will now raise you by at least one priority with each wakeup. This causes
> massive differences to startup time, extremely rapid conversion to interactive
> state, and recovery from non-interactive state rapidly as well (prevents X
> stalling after thrashing around under high loads for many seconds).
>
> The sleep buffer was dropped to just 10ms. This has the effect of causing mild
> round robinning of very interactive tasks if they run for more than 10ms. The
> requeuing was changed from (unlikely()) to an ordinary if.. branch as this
> will be hit much more now.
>
> MAX_BONUS as a #define was made easier to understand
>
> Idle tasks were made slightly less interactive to prevent cpu hogs from
> becoming interactive on their very first wakeup.
>
> Con
>
> This patch-O6int-0307170012 applies on top of 2.6.0-test1-mm1 and can be found
> here:
> http://kernel.kolivas.org/2.5
>
> and here:
>
> --- linux-2.6.0-test1-mm1/kernel/sched.c 2003-07-16 20:27:32.000000000 +1000
> +++ linux-2.6.0-testck1/kernel/sched.c 2003-07-17 00:13:24.000000000 +1000
> @@ -76,9 +76,9 @@
> #define MIN_SLEEP_AVG (HZ)
> #define MAX_SLEEP_AVG (10*HZ)
> #define STARVATION_LIMIT (10*HZ)
> -#define SLEEP_BUFFER (HZ/20)
> +#define SLEEP_BUFFER (HZ/100)
> #define NODE_THRESHOLD 125
> -#define MAX_BONUS ((MAX_USER_PRIO - MAX_RT_PRIO) * PRIO_BONUS_RATIO / 100)
> +#define MAX_BONUS (40 * PRIO_BONUS_RATIO / 100)
>
> /*
> * If a task is 'interactive' then we reinsert it in the active
> @@ -399,7 +399,7 @@ static inline void activate_task(task_t
> */
> if (sleep_time > MIN_SLEEP_AVG){
> p->avg_start = jiffies - MIN_SLEEP_AVG;
> - p->sleep_avg = MIN_SLEEP_AVG * (MAX_BONUS - INTERACTIVE_DELTA - 1) /
> + p->sleep_avg = MIN_SLEEP_AVG * (MAX_BONUS - INTERACTIVE_DELTA - 2) /
> MAX_BONUS;
> } else {
> /*
> @@ -413,14 +413,10 @@ static inline void activate_task(task_t
> p->sleep_avg += sleep_time;
>
> /*
> - * Give a bonus to tasks that wake early on to prevent
> - * the problem of the denominator in the bonus equation
> - * from continually getting larger.
> + * Processes that sleep get pushed to a higher priority
> + * each time they sleep
> */
> - if ((runtime - MIN_SLEEP_AVG) < MAX_SLEEP_AVG)
> - p->sleep_avg += (runtime - p->sleep_avg) *
> - (MAX_SLEEP_AVG + MIN_SLEEP_AVG - runtime) *
> - (MAX_BONUS - INTERACTIVE_DELTA) / MAX_BONUS / MAX_SLEEP_AVG;
> + p->sleep_avg = (p->sleep_avg * MAX_BONUS / runtime + 1) * runtime / MAX_BONUS;
>
> /*
> * Keep a small buffer of SLEEP_BUFFER sleep_avg to
> @@ -1311,7 +1307,7 @@ void scheduler_tick(int user_ticks, int
> enqueue_task(p, rq->expired);
> } else
> enqueue_task(p, rq->active);
> - } else if (unlikely(p->prio < effective_prio(p))){
> + } else if (p->prio < effective_prio(p)){
> /*
> * Tasks that have lowered their priority are put to the end
> * of the active array with their remaining timeslice
>
> -
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Regards,

Wiktor Wodecki

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