On Wed, 24 Jun 2015 16:19:33 -0700
Cong Wang <xiyou.wangc...@gmail.com> wrote:
> For compatibility, the sched_switch event is not touched.
Yes, and sched_out() should not be added.
>
> Cc: Steven Rostedt <rost...@goodmis.org>
> Cc: Ingo Molnar <mi...@redhat.com>
> Cc: Peter Zijlstra <pet...@infradead.org>
> Signed-off-by: Cong Wang <xiyou.wangc...@gmail.com>
> Signed-off-by: Cong Wang <cw...@twopensource.com>
> ---
> include/trace/events/sched.h | 51
> +++++++++++++++++++++++++++++++++++++++++++-
> kernel/sched/core.c | 2 ++
> 2 files changed, 52 insertions(+), 1 deletion(-)
>
> diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
> index d57a575..c31f1e0 100644
> --- a/include/trace/events/sched.h
> +++ b/include/trace/events/sched.h
> @@ -112,8 +112,57 @@ static inline long __trace_sched_switch_state(struct
> task_struct *p)
> #endif /* CREATE_TRACE_POINTS */
>
> /*
> - * Tracepoint for task switches, performed by the scheduler:
> + * Tracepoints for task switches, performed by the scheduler:
> */
> +TRACE_EVENT(sched_out,
> +
> + TP_PROTO(struct task_struct *curr),
> +
> + TP_ARGS(curr),
> +
> + TP_STRUCT__entry(
> + __array( char, comm, TASK_COMM_LEN )
> + __field( int, prio )
> + __field( long, state )
> + ),
> +
> + TP_fast_assign(
> + __entry->prio = curr->prio;
> + __entry->state = __trace_sched_switch_state(curr);
> + memcpy(__entry->comm, curr->comm, TASK_COMM_LEN);
> + ),
> +
> + TP_printk("comm=%s prio=%d state=%s%s",
> + __entry->comm, __entry->prio,
> + __entry->state & (TASK_STATE_MAX-1) ?
> + __print_flags(__entry->state & (TASK_STATE_MAX-1), "|",
> + { 1, "S"} , { 2, "D" }, { 4, "T" }, { 8, "t" },
> + { 16, "Z" }, { 32, "X" }, { 64, "x" },
> + { 128, "K" }, { 256, "W" }, { 512, "P" },
> + { 1024, "N" }) : "R",
> + __entry->state & TASK_STATE_MAX ? "+" : "")
> +);
> +
> +TRACE_EVENT(sched_in,
> +
> + TP_PROTO(struct task_struct *next),
> +
> + TP_ARGS(next),
> +
> + TP_STRUCT__entry(
> + __array( char, comm, TASK_COMM_LEN )
> + __field( int, prio )
> + ),
> +
> + TP_fast_assign(
> + memcpy(__entry->comm, next->comm, TASK_COMM_LEN);
> + __entry->prio = next->prio;
> + ),
> +
> + TP_printk("comm=%s prio=%d",
> + __entry->comm, __entry->prio)
> +);
> +
> TRACE_EVENT(sched_switch,
>
> TP_PROTO(struct task_struct *prev,
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index c86935a..681fc50 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -2219,6 +2219,7 @@ prepare_task_switch(struct rq *rq, struct task_struct
> *prev,
> struct task_struct *next)
> {
> trace_sched_switch(prev, next);
> + trace_sched_out(prev);
Tracepoints are low overhead, but they do take up space. This is a
useless tracepoint. If anything, I'll work on adding an alias or
something. But please don't add a tracepoint next to a tracepoint that
encompasses the data.
> sched_info_switch(rq, prev, next);
> perf_event_task_sched_out(prev, next);
> fire_sched_out_preempt_notifiers(prev, next);
> @@ -2288,6 +2289,7 @@ static struct rq *finish_task_switch(struct task_struct
> *prev)
> }
>
> tick_nohz_task_switch(current);
> + trace_sched_in(current);
Why not have a:
sched_switch_post(prev, current);
That way, the hook can be useful for other tools.
-- Steve
> return rq;
> }
>
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