Commit f447c196 authored by Steven Rostedt (VMware)'s avatar Steven Rostedt (VMware)
Browse files

tracing: Clean up the hwlat binding code 



Instead of initializing the affinity of the hwlat kthread in the thread
itself, simply set up the initial affinity at thread creation. This
simplifies the code.

Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent 79c6f448

kernel/trace/trace_hwlat.c

+17 −17
Original line number Diff line number Diff line
@@ -266,24 +266,13 @@ static int get_sample(void) 
static struct cpumask save_cpumask;

static bool disable_migrate;



static void move_to_next_cpu(bool initmask)

static void move_to_next_cpu(void)

{

	static struct cpumask *current_mask;

	struct cpumask *current_mask = &save_cpumask;

	int next_cpu;



	if (disable_migrate)

		return;



	/* Just pick the first CPU on first iteration */

	if (initmask) {

		current_mask = &save_cpumask;

		get_online_cpus();

		cpumask_and(current_mask, cpu_online_mask, tracing_buffer_mask);

		put_online_cpus();

		next_cpu = cpumask_first(current_mask);

		goto set_affinity;

	}



	/*

	 * If for some reason the user modifies the CPU affinity

	 * of this thread, than stop migrating for the duration
@@ -300,7 +289,6 @@ static void move_to_next_cpu(bool initmask) 
	if (next_cpu >= nr_cpu_ids)

		next_cpu = cpumask_first(current_mask);



 set_affinity:

	if (next_cpu >= nr_cpu_ids) /* Shouldn't happen! */

		goto disable;
@@ -330,12 +318,10 @@ static void move_to_next_cpu(bool initmask) 
static int kthread_fn(void *data)

{

	u64 interval;

	bool initmask = true;



	while (!kthread_should_stop()) {



		move_to_next_cpu(initmask);

		initmask = false;

		move_to_next_cpu();



		local_irq_disable();

		get_sample();
@@ -366,13 +352,27 @@ static int kthread_fn(void *data) 
 */

static int start_kthread(struct trace_array *tr)

{

	struct cpumask *current_mask = &save_cpumask;

	struct task_struct *kthread;

	int next_cpu;



	/* Just pick the first CPU on first iteration */

	current_mask = &save_cpumask;

	get_online_cpus();

	cpumask_and(current_mask, cpu_online_mask, tracing_buffer_mask);

	put_online_cpus();

	next_cpu = cpumask_first(current_mask);



	kthread = kthread_create(kthread_fn, NULL, "hwlatd");

	if (IS_ERR(kthread)) {

		pr_err(BANNER "could not start sampling thread\n");

		return -ENOMEM;

	}



	cpumask_clear(current_mask);

	cpumask_set_cpu(next_cpu, current_mask);

	sched_setaffinity(kthread->pid, current_mask);



	hwlat_kthread = kthread;

	wake_up_process(kthread);