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Message-ID: <20250502015955.3146733-5-prakash.sangappa@oracle.com>
Date: Fri, 2 May 2025 01:59:55 +0000
From: Prakash Sangappa <prakash.sangappa@...cle.com>
To: linux-kernel@...r.kernel.org
Cc: peterz@...radead.org, rostedt@...dmis.org, mathieu.desnoyers@...icios.com,
tglx@...utronix.de, bigeasy@...utronix.de, kprateek.nayak@....com
Subject: [PATCH V3 4/4] Sched: Add tracepoint for sched time slice extension
Trace task's preemption due to a wakeups, getting delayed. Which
can occurs when the running task requested extra time on cpu.
Also, indicate the NEED_RESCHED flag set on the task getting
cleared.
Signed-off-by: Prakash Sangappa <prakash.sangappa@...cle.com>
---
include/trace/events/sched.h | 28 ++++++++++++++++++++++++++++
kernel/entry/common.c | 8 ++++++--
2 files changed, 34 insertions(+), 2 deletions(-)
diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
index 8994e97d86c1..4aa04044b14a 100644
--- a/include/trace/events/sched.h
+++ b/include/trace/events/sched.h
@@ -296,6 +296,34 @@ TRACE_EVENT(sched_migrate_task,
__entry->orig_cpu, __entry->dest_cpu)
);
+/*
+ * Tracepoint for delayed resched requested by task:
+ */
+TRACE_EVENT(sched_delay_resched,
+
+ TP_PROTO(struct task_struct *p, unsigned int resched_flg),
+
+ TP_ARGS(p, resched_flg),
+
+ TP_STRUCT__entry(
+ __array( char, comm, TASK_COMM_LEN )
+ __field( pid_t, pid )
+ __field( int, cpu )
+ __field( int, flg )
+ ),
+
+ TP_fast_assign(
+ memcpy(__entry->comm, p->comm, TASK_COMM_LEN);
+ __entry->pid = p->pid;
+ __entry->cpu = task_cpu(p);
+ __entry->flg = resched_flg;
+ ),
+
+ TP_printk("comm=%s pid=%d cpu=%d resched_flg_cleared=0x%x",
+ __entry->comm, __entry->pid, __entry->cpu, __entry->flg)
+
+);
+
DECLARE_EVENT_CLASS(sched_process_template,
TP_PROTO(struct task_struct *p),
diff --git a/kernel/entry/common.c b/kernel/entry/common.c
index b26adccb32df..1951e6a4e9bc 100644
--- a/kernel/entry/common.c
+++ b/kernel/entry/common.c
@@ -12,6 +12,7 @@
#include "common.h"
+#include <trace/events/sched.h>
#define CREATE_TRACE_POINTS
#include <trace/events/syscalls.h>
@@ -100,9 +101,12 @@ __always_inline unsigned long exit_to_user_mode_loop(struct pt_regs *regs,
local_irq_enable_exit_to_user(ti_work);
if (ti_work & (_TIF_NEED_RESCHED | _TIF_NEED_RESCHED_LAZY)) {
- if (irq && rseq_delay_resched())
+ if (irq && rseq_delay_resched()) {
clear_tsk_need_resched(current);
- else
+ trace_sched_delay_resched(current,
+ ti_work & (_TIF_NEED_RESCHED |
+ _TIF_NEED_RESCHED_LAZY));
+ } else
schedule();
}
--
2.43.5
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