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sched/deadline: Add latency tracing for SCHED_DEADLINE tasks

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It is very likely that systems that wants/needs to use the new
SCHED_DEADLINE policy also want to have the scheduling latency of
the -deadline tasks under control.

For this reason a new version of the scheduling wakeup latency,
called "wakeup_dl", is introduced.

As a consequence of applying this patch there will be three wakeup
latency tracer:

 * "wakeup", that deals with all tasks in the system;
 * "wakeup_rt", that deals with -rt and -deadline tasks only;
 * "wakeup_dl", that deals with -deadline tasks only.

Signed-off-by: Dario Faggioli <raistlin@linux.it>
Signed-off-by: Juri Lelli <juri.lelli@gmail.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1383831828-15501-9-git-send-email-juri.lelli@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Dario Faggioli
2013-11-07 14:43:42 +01:00
committed by Ingo Molnar
parent 755378a471
commit af6ace764d
2 changed files with 79 additions and 18 deletions
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33
kernel/trace/trace_selftest.c
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@@ -1022,11 +1022,16 @@ trace_selftest_startup_nop(struct tracer *trace, struct trace_array *tr)
#ifdef CONFIG_SCHED_TRACER
static int trace_wakeup_test_thread(void *data)
{
/* Make this a RT thread, doesn't need to be too high */
static const struct sched_param param = { .sched_priority = 5 };
/* Make this a -deadline thread */
static const struct sched_attr attr = {
.sched_policy = SCHED_DEADLINE,
.sched_runtime = 100000ULL,
.sched_deadline = 10000000ULL,
.sched_period = 10000000ULL
};
struct completion *x = data;
sched_setscheduler(current, SCHED_FIFO, &param);
sched_setattr(current, &attr);
/* Make it know we have a new prio */
complete(x);
@@ -1040,8 +1045,8 @@ static int trace_wakeup_test_thread(void *data)
/* we are awake, now wait to disappear */
while (!kthread_should_stop()) {
/*
* This is an RT task, do short sleeps to let
* others run.
* This will likely be the system top priority
* task, do short sleeps to let others run.
*/
msleep(100);
}
@@ -1054,21 +1059,21 @@ trace_selftest_startup_wakeup(struct tracer *trace, struct trace_array *tr)
{
unsigned long save_max = tracing_max_latency;
struct task_struct *p;
struct completion isrt;
struct completion is_ready;
unsigned long count;
int ret;
init_completion(&isrt);
init_completion(&is_ready);
/* create a high prio thread */
p = kthread_run(trace_wakeup_test_thread, &isrt, "ftrace-test");
/* create a -deadline thread */
p = kthread_run(trace_wakeup_test_thread, &is_ready, "ftrace-test");
if (IS_ERR(p)) {
printk(KERN_CONT "Failed to create ftrace wakeup test thread ");
return -1;
}
/* make sure the thread is running at an RT prio */
wait_for_completion(&isrt);
/* make sure the thread is running at -deadline policy */
wait_for_completion(&is_ready);
/* start the tracing */
ret = tracer_init(trace, tr);
@@ -1082,19 +1087,19 @@ trace_selftest_startup_wakeup(struct tracer *trace, struct trace_array *tr)
while (p->on_rq) {
/*
* Sleep to make sure the RT thread is asleep too.
* Sleep to make sure the -deadline thread is asleep too.
* On virtual machines we can't rely on timings,
* but we want to make sure this test still works.
*/
msleep(100);
}
init_completion(&isrt);
init_completion(&is_ready);
wake_up_process(p);
/* Wait for the task to wake up */
wait_for_completion(&isrt);
wait_for_completion(&is_ready);
/* stop the tracing. */
tracing_stop();