From: Daniel Bristot de Oliveira bristot@kernel.org
[ 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/302aa6c7bdf2d131719b22901905e9da122a11b2.164519733...
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 --- kernel/trace/trace_osnoise.c | 53 ++++++++++++++++++++++-------------- 1 file changed, 32 insertions(+), 21 deletions(-)
diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c index 65a518649997..fc491d0aee5a 100644 --- a/kernel/trace/trace_osnoise.c +++ b/kernel/trace/trace_osnoise.c @@ -1249,6 +1249,37 @@ static int run_osnoise(void) 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;