linux-kernel - [PATCH] tracing/sched: add 'next_policy' to trace_sched

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Message-Id: <20250822105113.1102099-1-gxxa03070307@gmail.com>
Date: Fri, 22 Aug 2025 18:51:13 +0800
From: Xiang Gao <gxxa03070307@...il.com>
To: rostedt@...dmis.org,
	mhiramat@...nel.org
Cc: mathieu.desnoyers@...icios.com,
	andrii@...nel.org,
	mingo@...nel.org,
	oleg@...hat.com,
	akpm@...ux-foundation.org,
	gmonaco@...hat.com,
	ricardo.neri-calderon@...ux.intel.com,
	libo.chen@...cle.com,
	linux-kernel@...r.kernel.org,
	linux-trace-kernel@...r.kernel.org,
	gaoxiang17 <gaoxiang17@...omi.com>
Subject: [PATCH] tracing/sched: add 'next_policy' to trace_sched_switch

From: gaoxiang17 <gaoxiang17@...omi.com>

Sometimes, when analyzing some real-time process issues, it is necessary to know the sched policy.

Show up in the trace as:

      113.457176: sched_switch: prev_comm=kcompactd0 prev_pid=30 prev_prio=120 prev_state=S ==> next_comm=kworker/u4:1 next_pid=27 next_prio=120 next_policy=0
      113.457282: sched_switch: prev_comm=kworker/u4:1 prev_pid=27 prev_prio=120 prev_state=I ==> next_comm=swapper/0 next_pid=0 next_prio=120 next_policy=0
      113.461166: sched_switch: prev_comm=swapper/0 prev_pid=0 prev_prio=120 prev_state=R ==> next_comm=kworker/u4:1 next_pid=27 next_prio=120 next_policy=0

Signed-off-by: gaoxiang17 <gaoxiang17@...omi.com>
---
 include/trace/events/sched.h | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
index 7b2645b50e78..b416b7bafee4 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=%u",
 		__entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
 
 		(__entry->prev_state & (TASK_REPORT_MAX - 1)) ?
@@ -263,7 +265,7 @@ 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, __entry->next_policy)
 );
 
 /*
-- 
2.34.1