void stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fxn, void *arg,
struct cpu_stop_work *work_buf)
{
struct task_struct *stop = stop_tasks[cpu];
struct stop_task *stop_task = task_thread_info(stop)->td->data;
int this_cpu = smp_processor_id();
/*
* catch a data race on simultaneous calls to stop_one_cpu_nowait, if
* this ends up happening we'd need to support a proper queue here.
*/
BUG_ON(stop_task->fxn);
stop_task->fxn = fxn;
stop_task->arg = arg;
/*
* in the nowait case we actually go through a schedule to make sure
* that our cpu has a change to drop its rq->locks since they may be
* needed.
*/
linsched_change_cpu(cpu);
hrtimer_set_expires(&stop_task->timer, ns_to_ktime(1));
hrtimer_start_expires(&stop_task->timer, HRTIMER_MODE_REL);
linsched_change_cpu(this_cpu);
}
/* Force a migration of task to the dest_cpu.
* If migr is set, allow migrations after the forced migration... otherwise,
* do not allow them. (We need to disable migrations so that the forced
* migration takes place correctly.)
* Returns old cpu of task.
*/
int linsched_force_migration(struct task_struct *task, int dest_cpu, int migr)
{
int old_cpu = task_cpu(task);
linsched_disable_migrations();
set_cpus_allowed(task, cpumask_of_cpu(dest_cpu));
linsched_change_cpu(old_cpu);
schedule();
linsched_change_cpu(dest_cpu);
schedule();
if (migr)
linsched_enable_migrations();
return old_cpu;
}
/* kernel/smp.c */
void __smp_call_function_single(int cpu, struct call_single_data *data,
int wait)
{
int this_cpu = smp_processor_id();
unsigned long flags;
if (cpu != this_cpu)
linsched_change_cpu(cpu);
local_irq_save(flags);
data->func(data->info);
local_irq_restore(flags);
if (cpu != this_cpu)
linsched_change_cpu(this_cpu);
}
int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fxn, void *arg)
{
struct task_struct *stop = stop_tasks[cpu];
int this_cpu = smp_processor_id(), ret;
linsched_change_cpu(cpu);
wake_up_process(stop);
/* switch to stop */
schedule();
BUG_ON(current != stop);
ret = fxn(arg);
/* switch back */
stop->state = TASK_INTERRUPTIBLE;
schedule();
/* let whoever followed the stop task re-program (if needed) */
linsched_current_handler();
BUG_ON(current == stop);
linsched_change_cpu(this_cpu);
return ret;
}
void linsched_run_sim(int sim_ticks)
{
/* Run a simulation for some number of ticks. Each tick,
* scheduling and load balancing decisions are made. The
* order in which CPUs make their scheduler_tick calls
* is randomized. Obviously, we could create tasks,
* change priorities, etc., at certain ticks if we desired,
* rather than just running a simple simulation.
* (Tasks can also be removed by having them exit.)
*/
/* NOTE: The per-CPU "tick" is never disabled, like it might be in a
* real system, when a CPU goes idle. Since even the most current
* version of Linux maintains a periodic tick when there is
* actual work to do, and disabling the tick when idle would
* not change anything about how the scheduler behaves
* (it only conserves energy, which is not going to help us here),
* there is no need.
*/
// printf("Yeah-first_run\n");
int initial_jiffies = jiffies;
for (jiffies = initial_jiffies;
jiffies < initial_jiffies + sim_ticks;
jiffies++) {
cpumask_t cpu_processed_map = CPU_MASK_NONE;
while (!cpus_full(cpu_processed_map)) {
int active_cpu;
/* Determine next active CPU, and set as processed. */
do {
active_cpu = linsched_random() % NR_CPUS;
//active_cpu = 1;
} while (cpu_isset(active_cpu, cpu_processed_map));
cpu_set(active_cpu, cpu_processed_map);
/* Call scheduler_tick for that CPU. */
linsched_change_cpu(active_cpu);
// printf("Mainsimulation\n");
scheduler_tick(); /* may trigger a schedule() call */
/* First time executing a task? Do not need to
* call schedule_tail, since we are not actually
* performing a "real" context switch.
*/
}
}
}
void linsched_init(void)
{
/* Initialize platform. For now, this does nothing, since
* the number of CPUs is known, and we do not yet support
* MC/SMT/NUMA. Scheduling decisions are not dependent on
* asymmetries yet, either, but that could change.
*/
linsched_init_cpus();
/* Initialize random number generator. */
linsched_random_init(LINSCHED_RAND_SEED);
/* Change context to "boot" cpu and boot kernel. */
linsched_change_cpu(0);
start_kernel();
}