diff options
Diffstat (limited to 'kernel/trace/trace_hwlat.c')
| -rw-r--r-- | kernel/trace/trace_hwlat.c | 40 |
1 files changed, 19 insertions, 21 deletions
diff --git a/kernel/trace/trace_hwlat.c b/kernel/trace/trace_hwlat.c index af344a1bf0d0..21ea6ae77d93 100644 --- a/kernel/trace/trace_hwlat.c +++ b/kernel/trace/trace_hwlat.c @@ -44,6 +44,7 @@ #include <linux/uaccess.h> #include <linux/cpumask.h> #include <linux/delay.h> +#include <linux/sched/clock.h> #include "trace.h" static struct trace_array *hwlat_trace; @@ -266,24 +267,13 @@ out: 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 +290,6 @@ 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; @@ -322,20 +311,15 @@ static void move_to_next_cpu(bool initmask) * need to ensure nothing else might be running (and thus preempting). * Obviously this should never be used in production environments. * - * Currently this runs on which ever CPU it was scheduled on, but most - * real-world hardware latency situations occur across several CPUs, - * but we might later generalize this if we find there are any actualy - * systems with alternate SMI delivery or other hardware latencies. + * Executes one loop interaction on each CPU in tracing_cpumask sysfs file. */ 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 +350,27 @@ 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); |