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tracing/osnoise: Add OSNOISE_WORKLOAD option 

The osnoise tracer is not only a tracer, and a set of tracepoints,
but also a workload dispatcher.

In preparation for having other workloads, e.g., in user-space,
add an option to avoid dispatching the workload.

By not dispatching the workload, the osnoise: tracepoints become
generic events to measure the execution time of *any* task on Linux.

For example:

  # cd /sys/kernel/tracing/
  # cat osnoise/options
  DEFAULTS OSNOISE_WORKLOAD
  # echo NO_OSNOISE_WORKLOAD > osnoise/options
  # cat osnoise/options
  NO_DEFAULTS NO_OSNOISE_WORKLOAD
  # echo osnoise > set_event
  # echo osnoise > current_tracer
  # tail -8 trace
      make-94722   [002] d..3.  1371.794507: thread_noise:     make:94722 start 1371.794302286 duration 200897 ns
        sh-121042  [020] d..3.  1371.794534: thread_noise:       sh:121042 start 1371.781610976 duration 8943683 ns
      make-121097  [005] d..3.  1371.794542: thread_noise:     make:121097 start 1371.794481522 duration 60444 ns
     <...>-40      [005] d..3.  1371.794550: thread_noise: migration/5:40 start 1371.794542256 duration 7154 ns
    <idle>-0       [018] dNh2.  1371.794554: irq_noise: reschedule:253 start 1371.794553547 duration 40 ns
    <idle>-0       [018] dNh2.  1371.794561: irq_noise: local_timer:236 start 1371.794556222 duration 4890 ns
    <idle>-0       [018] .Ns2.  1371.794563: softirq_noise:    SCHED:7 start 1371.794561803 duration 992 ns
    <idle>-0       [018] d..3.  1371.794566: thread_noise: swapper/18:0 start 1371.781368110 duration 13191798 ns

In preparation for the rtla exec_time tracer/tool and
rtla osnoise --user option.

Link: https://lkml.kernel.org/r/f5cfbd37aefd419eefe9243b4d2fc38ed5753fe4.1668692096.git.bristot@kernel.org

Cc: Daniel Bristot de Oliveira <bristot@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Daniel Bristot de Oliveira 2022-11-17 14:46:19 +01:00 committed by Steven Rostedt (Google)
parent b179d48b6a
commit 30838fcd81
1 changed files with 22 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

28
kernel/trace/trace_osnoise.c
View File

@ -53,12 +53,13 @@
*/
enum osnoise_options_index {
OSN_DEFAULTS = 0,
OSN_WORKLOAD,
OSN_MAX
};
static const char * const osnoise_options_str[OSN_MAX] = { "DEFAULTS" };
static const char * const osnoise_options_str[OSN_MAX] = { "DEFAULTS", "OSNOISE_WORKLOAD" };
#define OSN_DEFAULT_OPTIONS 0
#define OSN_DEFAULT_OPTIONS 0x2
unsigned long osnoise_options = OSN_DEFAULT_OPTIONS;
/*
@ -1186,11 +1187,12 @@ trace_sched_switch_callback(void *data, bool preempt,
unsigned int prev_state)
{
struct osnoise_variables *osn_var = this_cpu_osn_var();
int workload = test_bit(OSN_WORKLOAD, &osnoise_options);
if (p->pid != osn_var->pid)
if ((p->pid != osn_var->pid) || !workload)
thread_exit(osn_var, p);
if (n->pid != osn_var->pid)
if ((n->pid != osn_var->pid) || !workload)
thread_entry(osn_var, n);
}
@ -1723,9 +1725,16 @@ static void stop_kthread(unsigned int cpu)
struct task_struct *kthread;
kthread = per_cpu(per_cpu_osnoise_var, cpu).kthread;
if (kthread)
if (kthread) {
kthread_stop(kthread);
per_cpu(per_cpu_osnoise_var, cpu).kthread = NULL;
per_cpu(per_cpu_osnoise_var, cpu).kthread = NULL;
} else {
if (!test_bit(OSN_WORKLOAD, &osnoise_options)) {
per_cpu(per_cpu_osnoise_var, cpu).sampling = false;
barrier();
return;
}
}
}
/*
@ -1759,6 +1768,13 @@ static int start_kthread(unsigned int cpu)
snprintf(comm, 24, "timerlat/%d", cpu);
main = timerlat_main;
} else {
/* if no workload, just return */
if (!test_bit(OSN_WORKLOAD, &osnoise_options)) {
per_cpu(per_cpu_osnoise_var, cpu).sampling = true;
barrier();
return 0;
}
snprintf(comm, 24, "osnoise/%d", cpu);
}