[LTP] [PATCH 3/6] sched_football: Re-add the crazy fans to interrupt everyone

[Cyril Hrubis]

Hi!
>   *      This is a scheduler test that uses a football analogy.
>   *      The premise is that we want to make sure that lower priority threads
> - *      (defensive team). The offense is trying to increment the balls position,
> - *      while the defense is trying to block that from happening.
> + *      don't run while we have runnable higher priority threads.
> + *      The offense is trying to increment the balls position, while the
> + *      defense is trying to block that from happening.
>   *      And the ref (highest priority thread) will blow the wistle if the
>   *      ball moves. Finally, we have crazy fans (higer prority) that try to
>   *      distract the defense by occasionally running onto the field.
>   *
>   *      Steps:
> - *       - Create a fixed number of offense threads (lower priority)
> + *       - Create NR_CPU offense threads (lower priority)
> + *       - Create NR_CPU defense threads (mid priority)
> + *       - Create 2*NR_CPU fan threads (high priority)
>   *       - Create a referee thread (highest priority)
> - *       - Once everyone is on the field, the offense thread increments the
> - *         value of 'the_ball'. The defense thread tries to block
> - *         the ball by never letting the offense players get the CPU (it just
> - *         spins).
> + *       - Once everyone is on the field, the offense thread spins incrementing
> + *         the value of 'the_ball'. The defense thread tries to block the ball
> + *         by never letting the offense players get the CPU (it just spins).
> + *         The crazy fans sleep a bit, then jump the rail and run across the
> + *         field, disrupting the players on the field.
>   *       - The refree threads wakes up regularly to check if the game is over :)
>   *       - In the end, if the value of 'the_ball' is >0, the test is considered
>   *         to have failed.
> @@ -52,7 +56,7 @@
>   *		bugfixes and cleanups. -- Josh Triplett
>   *     2009-06-23 Simplified atomic startup mechanism, avoiding thundering herd
>   *		scheduling at the beginning of the game. -- Darren Hart
> - *
> + *     2024-04-23 Re-add crazy fans! Along with minor cleanups -- John Stultz

We use git now, so it's kind of pointless to add more changelog lines
into the file itself.

>   *****************************************************************************/
>  
>  #include <stdio.h>
> @@ -107,6 +111,38 @@ int parse_args(int c, char *v)
>  	return handled;
>  }
>  
> +#define NSEC_PER_SEC 1000000000ULL
> +unsigned long long ts_delta(struct timespec *start, struct timespec *stop)
> +{
> +	unsigned long long a, b;
> +
> +	a = start->tv_sec * NSEC_PER_SEC + start->tv_nsec;
> +	b = stop->tv_sec * NSEC_PER_SEC + stop->tv_nsec;
> +	return b - a;
> +}

This is tst_timespec_diff() from include/tst_timer.h

> +#define SPIN_TIME_NS 200000000
> +#define SLEEP_TIME_NS 50000000
> +/* These are fans running across the field. They're trying to interrupt/distract everyone */
> +void *thread_fan(void *arg)
> +{
> +	atomic_inc(&players_ready);
> +	/*occasionally wake up and run across the field */
> +	while (1) {
> +		int i;
> +		struct timespec start, stop;
> +
> +		start.tv_sec = 0;
> +		start.tv_nsec = SLEEP_TIME_NS;
> +		clock_nanosleep(CLOCK_MONOTONIC, 0, &start, NULL);
> +		clock_gettime(CLOCK_MONOTONIC, &start);
> +		clock_gettime(CLOCK_MONOTONIC, &stop);
> +		while (ts_delta(&start, &stop) < SPIN_TIME_NS)
> +			clock_gettime(CLOCK_MONOTONIC, &stop);
> +	}
> +	return NULL;
> +}
> +
>  /* This is the defensive team. They're trying to block the offense */
>  void *thread_defense(void *arg)
>  {
> @@ -199,6 +235,17 @@ int main(int argc, char *argv[])
>  	while (atomic_get(&players_ready) < players_per_team * 2)
>  		usleep(100);
>  
> +	/* Start the crazy fans*/
> +	priority = 50;
> +	printf("Starting %d fan threads at priority %d\n",
> +	       players_per_team, priority);
> +	for (i = 0; i < players_per_team*2; i++)
> +		create_fifo_thread(thread_fan, NULL, priority);
> +
> +	/* Wait for the crazy fan threads to start */
> +	while (atomic_get(&players_ready) < players_per_team * 4)
> +		usleep(100);
> +
>  	/* Ok, everyone is on the field, bring out the ref */
>  	printf("Starting referee thread\n");
>  	result = referee(game_length);
> -- 
> 2.44.0.769.g3c40516874-goog
> 
> 
> -- 
> Mailing list info: https://lists.linux.it/listinfo/ltp

-- 
Cyril Hrubis
chrubis@suse.cz