[V4,02/19] trace/osnoise: Split workload start from the tracer start

Commit Message

Daniel Bristot de Oliveira Oct. 21, 2021, 12:56 p.m. UTC

In preparation from supporting multiple trace instances, create
workload start/stop specific functions.

No functional change.

Cc: Steven Rostedt <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Tom Zanussi <[e-mail]>
Cc: Masami Hiramatsu <[e-mail]>
Cc: Juri Lelli <[e-mail]>
Cc: Clark Williams <[e-mail]>
Cc: John Kacur <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: Sebastian Andrzej Siewior <[e-mail]>
Cc: Daniel Bristot de Oliveira <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Signed-off-by: Daniel Bristot de Oliveira <[e-mail]>
---
 kernel/trace/trace_osnoise.c | 53 ++++++++++++++++++++++--------------
 1 file changed, 33 insertions(+), 20 deletions(-)

Comments

Steven Rostedt Oct. 23, 2021, 2:25 a.m. UTC | #1

On Thu, 21 Oct 2021 14:56:40 +0200
Daniel Bristot de Oliveira <[e-mail]> wrote:

> +/*
> + * osnoise_workload_stop - stop the workload and unhook the events
> + */
> +static void osnoise_workload_stop(void)
> +{
> +	if (!osnoise_busy)
> +		return;
> +
> +	trace_osnoise_callback_enabled = false;

I know this is just moving this code, but the original code had this
issue too, but there should be a comment here to why we need the
compiler barrier.

-- Steve


> +	barrier();
> +
> +	stop_per_cpu_kthreads();
> +
> +	unhook_irq_events();
> +	unhook_softirq_events();
> +	unhook_thread_events();
> +
> +	osnoise_busy = false;
> +}
> +

Daniel Bristot de Oliveira Oct. 25, 2021, 7:33 a.m. UTC | #2

On 10/23/21 04:25, Steven Rostedt wrote:
> On Thu, 21 Oct 2021 14:56:40 +0200
> Daniel Bristot de Oliveira <[e-mail]> wrote:
> 
>> +/*
>> + * osnoise_workload_stop - stop the workload and unhook the events
>> + */
>> +static void osnoise_workload_stop(void)
>> +{
>> +	if (!osnoise_busy)
>> +		return;
>> +
>> +	trace_osnoise_callback_enabled = false;
> 
> I know this is just moving this code, but the original code had this
> issue too, but there should be a comment here to why we need the
> compiler barrier.

I will add a comment, like we have on hwlat.

-- Daniel

> -- Steve
> 
> 
>> +	barrier();
>> +
>> +	stop_per_cpu_kthreads();
>> +
>> +	unhook_irq_events();
>> +	unhook_softirq_events();
>> +	unhook_thread_events();
>> +
>> +	osnoise_busy = false;
>> +}
>> +

Patch

diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c
index 7b1f8187764c..0a04a9a4c85a 100644
--- a/kernel/trace/trace_osnoise.c
+++ b/kernel/trace/trace_osnoise.c
@@ -1545,7 +1545,7 @@  static int start_kthread(unsigned int cpu)
  * This starts the kernel thread that will look for osnoise on many
  * cpus.
  */
-static int start_per_cpu_kthreads(struct trace_array *tr)
+static int start_per_cpu_kthreads(void)
 {
 	struct cpumask *current_mask = &save_cpumask;
 	int retval = 0;
@@ -1678,8 +1678,8 @@  osnoise_cpus_read(struct file *filp, char __user *ubuf, size_t count,
 	return count;
 }
 
-static void osnoise_tracer_start(struct trace_array *tr);
-static void osnoise_tracer_stop(struct trace_array *tr);
+static int osnoise_workload_start(void);
+static void osnoise_workload_stop(void);
 
 /*
  * osnoise_cpus_write - Write function for "cpus" entry
@@ -1701,7 +1701,6 @@  static ssize_t
 osnoise_cpus_write(struct file *filp, const char __user *ubuf, size_t count,
 		   loff_t *ppos)
 {
-	struct trace_array *tr = osnoise_trace;
 	cpumask_var_t osnoise_cpumask_new;
 	int running, err;
 	char buf[256];
@@ -1726,7 +1725,7 @@  osnoise_cpus_write(struct file *filp, const char __user *ubuf, size_t count,
 	mutex_lock(&trace_types_lock);
 	running = osnoise_busy;
 	if (running)
-		osnoise_tracer_stop(tr);
+		osnoise_workload_stop();
 
 	mutex_lock(&interface_lock);
 	/*
@@ -1740,7 +1739,7 @@  osnoise_cpus_write(struct file *filp, const char __user *ubuf, size_t count,
 	mutex_unlock(&interface_lock);
 
 	if (running)
-		osnoise_tracer_start(tr);
+		osnoise_workload_start();
 	mutex_unlock(&trace_types_lock);
 
 	free_cpumask_var(osnoise_cpumask_new);
@@ -1921,7 +1920,10 @@  static int osnoise_hook_events(void)
 	return -EINVAL;
 }
 
-static int __osnoise_tracer_start(struct trace_array *tr)
+/*
+ * osnoise_workload_start - start the workload and hook to events
+ */
+static int osnoise_workload_start(void)
 {
 	int retval;
 
@@ -1936,7 +1938,7 @@  static int __osnoise_tracer_start(struct trace_array *tr)
 	barrier();
 	trace_osnoise_callback_enabled = true;
 
-	retval = start_per_cpu_kthreads(tr);
+	retval = start_per_cpu_kthreads();
 	if (retval) {
 		unhook_irq_events();
 		return retval;
@@ -1947,6 +1949,26 @@  static int __osnoise_tracer_start(struct trace_array *tr)
 	return 0;
 }
 
+/*
+ * osnoise_workload_stop - stop the workload and unhook the events
+ */
+static void osnoise_workload_stop(void)
+{
+	if (!osnoise_busy)
+		return;
+
+	trace_osnoise_callback_enabled = false;
+	barrier();
+
+	stop_per_cpu_kthreads();
+
+	unhook_irq_events();
+	unhook_softirq_events();
+	unhook_thread_events();
+
+	osnoise_busy = false;
+}
+
 static void osnoise_tracer_start(struct trace_array *tr)
 {
 	int retval;
@@ -1954,7 +1976,7 @@  static void osnoise_tracer_start(struct trace_array *tr)
 	if (osnoise_busy)
 		return;
 
-	retval = __osnoise_tracer_start(tr);
+	retval = osnoise_workload_start();
 	if (retval)
 		pr_err(BANNER "Error starting osnoise tracer\n");
 
@@ -1965,16 +1987,7 @@  static void osnoise_tracer_stop(struct trace_array *tr)
 	if (!osnoise_busy)
 		return;
 
-	trace_osnoise_callback_enabled = false;
-	barrier();
-
-	stop_per_cpu_kthreads();
-
-	unhook_irq_events();
-	unhook_softirq_events();
-	unhook_thread_events();
-
-	osnoise_busy = false;
+	osnoise_workload_stop();
 }
 
 static int osnoise_tracer_init(struct trace_array *tr)
@@ -2017,7 +2030,7 @@  static void timerlat_tracer_start(struct trace_array *tr)
 
 	osnoise_data.timerlat_tracer = 1;
 
-	retval = __osnoise_tracer_start(tr);
+	retval = osnoise_workload_start();
 	if (retval)
 		goto out_err;