Messages in this thread Patch in this message | | | Date | Mon, 30 May 2016 13:18:20 +0000 (UTC) | From | Mathieu Desnoyers <> | Subject | Re: [RFC PATCH 2/2] tracing: add sched_set_prio tracepoint |
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----- On May 27, 2016, at 5:16 PM, Julien Desfossez jdesfossez@efficios.com wrote:
> This tracepoint allows to keep track of all priority changes made by all > sites that can change this value. The impacted system calls are > sched_setscheduler, sched_setattr, sched_process_fork and set_user_nice. > The priority inheritance mechanism from rt_mutex gets also instrumented > with this tracepoint even though there is a dedicated tracepoint for it > (sched_pi_setprio). > > This allows analysis of real-time scheduling delays per thread priority, > which cannot be performed accurately if we only trace the priority of > the currently scheduled processes. > > Here is an example of what is output by ftrace when we change the > priority of a running process: > sys_sched_setscheduler(pid: 1c52, policy: 2, param: 7ffc22e20980) > sched_set_prio: comm=burnP6 pid=7250 oldprio=120 newprio=39 > sys_sched_setscheduler -> 0x0 > sched_switch: prev_comm=chrt prev_pid=7268 prev_prio=120 > prev_state=R ==> next_comm=burnP6 next_pid=7250 > next_prio=39 > > Signed-off-by: Julien Desfossez <jdesfossez@efficios.com>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
> --- > include/trace/events/sched.h | 21 ++++++++++++++++----- > kernel/sched/core.c | 1 + > 2 files changed, 17 insertions(+), 5 deletions(-) > > diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h > index 9b90c57..3b83ddb 100644 > --- a/include/trace/events/sched.h > +++ b/include/trace/events/sched.h > @@ -407,11 +407,7 @@ DEFINE_EVENT(sched_stat_runtime, sched_stat_runtime, > TP_PROTO(struct task_struct *tsk, u64 runtime, u64 vruntime), > TP_ARGS(tsk, runtime, vruntime)); > > -/* > - * Tracepoint for showing priority inheritance modifying a tasks > - * priority. > - */ > -TRACE_EVENT(sched_pi_setprio, > +DECLARE_EVENT_CLASS(sched_prio_template, > > TP_PROTO(struct task_struct *tsk, int newprio), > > @@ -436,6 +432,21 @@ TRACE_EVENT(sched_pi_setprio, > __entry->oldprio, __entry->newprio) > ); > > +/* > + * Tracepoint for showing priority inheritance modifying a tasks > + * priority. > + */ > +DEFINE_EVENT(sched_prio_template, sched_pi_setprio, > + TP_PROTO(struct task_struct *tsk, int newprio), > + TP_ARGS(tsk, newprio)); > + > +/* > + * Tracepoint for priority changes of a task. > + */ > +DEFINE_EVENT(sched_prio_template, sched_set_prio, > + TP_PROTO(struct task_struct *tsk, int newprio), > + TP_ARGS(tsk, newprio)); > + > #ifdef CONFIG_DETECT_HUNG_TASK > TRACE_EVENT(sched_process_hang, > TP_PROTO(struct task_struct *tsk), > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index 6946b8f..45fbaab 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -2232,6 +2232,7 @@ int sysctl_schedstats(struct ctl_table *table, int write, > > static void sched_set_prio(struct task_struct *p, int prio) > { > + trace_sched_set_prio(p, prio); > p->prio = prio; > } > > -- > 1.9.1
-- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com
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