On Tue, 26 Aug 2025 20:48:54 +0800
Xiang Gao <[email protected]> wrote:

> From: gaoxiang17 <[email protected]>
> 
> Sometimes, when analyzing some real-time process issues, it is necessary to 
> know the sched policy.
> 
> Show up in the trace as:
> 
>        72.267374: sched_switch: prev_comm=grep prev_pid=67 prev_prio=19 
> prev_state=S ==> next_comm=cat next_pid=66 next_prio=120 next_policy=normal
>        72.267594: sched_switch: prev_comm=cat prev_pid=66 prev_prio=120 
> prev_state=R+ ==> next_comm=grep next_pid=67 next_prio=19 next_policy=RR
>       562.192567: sched_switch: prev_comm=grep prev_pid=85 prev_prio=19 
> prev_state=S ==> next_comm=cat next_pid=84 next_prio=120 next_policy=normal
>       562.192944: sched_switch: prev_comm=cat prev_pid=84 prev_prio=120 
> prev_state=R+ ==> next_comm=grep next_pid=85 next_prio=19 next_policy=FIFO
> 

Peter,

Are you OK with extending the sched switch tracepoint?

-- Steve

> Signed-off-by: gaoxiang17 <[email protected]>
> ---
>  include/trace/events/sched.h | 15 +++++++++++++--
>  1 file changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
> index 7b2645b50e78..00336211aca6 100644
> --- a/include/trace/events/sched.h
> +++ b/include/trace/events/sched.h
> @@ -234,6 +234,7 @@ TRACE_EVENT(sched_switch,
>               __array(        char,   next_comm,      TASK_COMM_LEN   )
>               __field(        pid_t,  next_pid                        )
>               __field(        int,    next_prio                       )
> +             __field(        unsigned int,   next_policy     )
>       ),
>  
>       TP_fast_assign(
> @@ -244,10 +245,11 @@ TRACE_EVENT(sched_switch,
>               memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
>               __entry->next_pid       = next->pid;
>               __entry->next_prio      = next->prio;
> +             __entry->next_policy    = next->policy;
>               /* XXX SCHED_DEADLINE */
>       ),
>  
> -     TP_printk("prev_comm=%s prev_pid=%d prev_prio=%d prev_state=%s%s ==> 
> next_comm=%s next_pid=%d next_prio=%d",
> +     TP_printk("prev_comm=%s prev_pid=%d prev_prio=%d prev_state=%s%s ==> 
> next_comm=%s next_pid=%d next_prio=%d next_policy=%s",
>               __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
>  
>               (__entry->prev_state & (TASK_REPORT_MAX - 1)) ?
> @@ -263,7 +265,16 @@ TRACE_EVENT(sched_switch,
>                 "R",
>  
>               __entry->prev_state & TASK_REPORT_MAX ? "+" : "",
> -             __entry->next_comm, __entry->next_pid, __entry->next_prio)
> +             __entry->next_comm, __entry->next_pid, __entry->next_prio,
> +             __print_symbolic(__entry->next_policy,
> +                             { SCHED_NORMAL,         "normal" },
> +                             { SCHED_FIFO,           "FIFO" },
> +                             { SCHED_RR,             "RR" },
> +                             { SCHED_BATCH,          "batch" },
> +                             { SCHED_IDLE,           "idle" },
> +                             { SCHED_DEADLINE,       "deadline" },
> +                             { SCHED_EXT,            "sched_ext"})
> +     )
>  );
>  
>  /*


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