tracing/osnoise: Make osnoise_main to sleep for microseconds

BugLink: https://bugs.launchpad.net/bugs/1966056
[ Upstream commit dd990352f01ee9a6c6eee152e5d11c021caccfe4 ]

osnoise's runtime and period are in the microseconds scale, but it is
currently sleeping in the millisecond's scale. This behavior roots in the
usage of hwlat as the skeleton for osnoise.

Make osnoise to sleep in the microseconds scale. Also, move the sleep to
a specialized function.

Link: https://lkml.kernel.org/r/302aa6c7bdf2d131719b22901905e9da122a11b2.1645197336.git.bristot@kernel.org
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>

diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c
index 65a518649997b457525370f92312c79f39ea800c..fc491d0aee5a07bab55b1032b862335be876a5ff 100644 (file)
--- a/kernel/trace/trace_osnoise.c
+++ b/kernel/trace/trace_osnoise.c
@@ -1249,6 +1249,37 @@ out:
 static struct cpumask osnoise_cpumask;
 static struct cpumask save_cpumask;
 
+/*
+ * osnoise_sleep - sleep until the next period
+ */
+static void osnoise_sleep(void)
+{
+       u64 interval;
+       ktime_t wake_time;
+
+       mutex_lock(&interface_lock);
+       interval = osnoise_data.sample_period - osnoise_data.sample_runtime;
+       mutex_unlock(&interface_lock);
+
+       /*
+        * differently from hwlat_detector, the osnoise tracer can run
+        * without a pause because preemption is on.
+        */
+       if (!interval) {
+               /* Let synchronize_rcu_tasks() make progress */
+               cond_resched_tasks_rcu_qs();
+               return;
+       }
+
+       wake_time = ktime_add_us(ktime_get(), interval);
+       __set_current_state(TASK_INTERRUPTIBLE);
+
+       while (schedule_hrtimeout_range(&wake_time, 0, HRTIMER_MODE_ABS)) {
+               if (kthread_should_stop())
+                       break;
+       }
+}
+
 /*
  * osnoise_main - The osnoise detection kernel thread
  *
@@ -1257,30 +1288,10 @@ static struct cpumask save_cpumask;
  */
 static int osnoise_main(void *data)
 {
-       u64 interval;
 
        while (!kthread_should_stop()) {
-
                run_osnoise();
-
-               mutex_lock(&interface_lock);
-               interval = osnoise_data.sample_period - osnoise_data.sample_runtime;
-               mutex_unlock(&interface_lock);
-
-               do_div(interval, USEC_PER_MSEC);
-
-               /*
-                * differently from hwlat_detector, the osnoise tracer can run
-                * without a pause because preemption is on.
-                */
-               if (interval < 1) {
-                       /* Let synchronize_rcu_tasks() make progress */
-                       cond_resched_tasks_rcu_qs();
-                       continue;
-               }
-
-               if (msleep_interruptible(interval))
-                       break;
+               osnoise_sleep();
        }
 
        return 0;