diff mbox series

[v5,1/9] sched: Add sched tracepoints for RV task model

Message ID 20250305140406.350227-2-gmonaco@redhat.com (mailing list archive)
State Needs ACK
Headers show
Series rv: Add scheduler specification monitors | expand

Commit Message

Gabriele Monaco March 5, 2025, 2:03 p.m. UTC 
Add the following tracepoints:
* sched_entry(bool preempt, ip)
    Called while entering __schedule
* sched_exit(bool is_switch, ip)
    Called while exiting __schedule
* sched_set_state(task, curr_state, state)
    Called when a task changes its state (to and from running)

These tracepoints are useful to describe the Linux task model and are
adapted from the patches by Daniel Bristot de Oliveira
(https://bristot.me/linux-task-model/).

Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
---
 include/linux/rv.h                 |  2 +-
 include/linux/sched.h              | 16 ++++++++++++++++
 include/trace/events/sched.h       | 13 +++++++++++++
 kernel/sched/core.c                | 23 ++++++++++++++++++++++-
 tools/verification/rv/include/rv.h |  2 +-
 5 files changed, 53 insertions(+), 3 deletions(-)

Comments

Steven Rostedt March 7, 2025, 5:38 p.m. UTC | #1 
Can I get an Acked-by from one of the scheduler maintainers?

-- Steve


On Wed,  5 Mar 2025 15:03:54 +0100
Gabriele Monaco <gmonaco@redhat.com> wrote:

> Add the following tracepoints:
> * sched_entry(bool preempt, ip)
>     Called while entering __schedule
> * sched_exit(bool is_switch, ip)
>     Called while exiting __schedule
> * sched_set_state(task, curr_state, state)
>     Called when a task changes its state (to and from running)
> 
> These tracepoints are useful to describe the Linux task model and are
> adapted from the patches by Daniel Bristot de Oliveira
> (https://bristot.me/linux-task-model/).
> 
> Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
> ---
>  include/linux/rv.h                 |  2 +-
>  include/linux/sched.h              | 16 ++++++++++++++++
>  include/trace/events/sched.h       | 13 +++++++++++++
>  kernel/sched/core.c                | 23 ++++++++++++++++++++++-
>  tools/verification/rv/include/rv.h |  2 +-
>  5 files changed, 53 insertions(+), 3 deletions(-)
> 
> diff --git a/include/linux/rv.h b/include/linux/rv.h
> index 8883b41d88ec4..55d458be53a4c 100644
> --- a/include/linux/rv.h
> +++ b/include/linux/rv.h
> @@ -7,7 +7,7 @@
>  #ifndef _LINUX_RV_H
>  #define _LINUX_RV_H
>  
> -#define MAX_DA_NAME_LEN	24
> +#define MAX_DA_NAME_LEN	32
>  
>  #ifdef CONFIG_RV
>  /*
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index 9632e3318e0d6..45a61a0b97903 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -46,6 +46,7 @@
>  #include <linux/rv.h>
>  #include <linux/livepatch_sched.h>
>  #include <linux/uidgid_types.h>
> +#include <linux/tracepoint-defs.h>
>  #include <asm/kmap_size.h>
>  
>  /* task_struct member predeclarations (sorted alphabetically): */
> @@ -186,6 +187,12 @@ struct user_event_mm;
>  # define debug_rtlock_wait_restore_state()	do { } while (0)
>  #endif
>  
> +#define trace_set_current_state(state_value)                     \
> +	do {                                                     \
> +		if (tracepoint_enabled(sched_set_state_tp))      \
> +			__trace_set_current_state(state_value); \
> +	} while (0)
> +
>  /*
>   * set_current_state() includes a barrier so that the write of current->__state
>   * is correctly serialised wrt the caller's subsequent test of whether to
> @@ -226,12 +233,14 @@ struct user_event_mm;
>  #define __set_current_state(state_value)				\
>  	do {								\
>  		debug_normal_state_change((state_value));		\
> +		trace_set_current_state(state_value);			\
>  		WRITE_ONCE(current->__state, (state_value));		\
>  	} while (0)
>  
>  #define set_current_state(state_value)					\
>  	do {								\
>  		debug_normal_state_change((state_value));		\
> +		trace_set_current_state(state_value);			\
>  		smp_store_mb(current->__state, (state_value));		\
>  	} while (0)
>  
> @@ -247,6 +256,7 @@ struct user_event_mm;
>  									\
>  		raw_spin_lock_irqsave(&current->pi_lock, flags);	\
>  		debug_special_state_change((state_value));		\
> +		trace_set_current_state(state_value);			\
>  		WRITE_ONCE(current->__state, (state_value));		\
>  		raw_spin_unlock_irqrestore(&current->pi_lock, flags);	\
>  	} while (0)
> @@ -282,6 +292,7 @@ struct user_event_mm;
>  		raw_spin_lock(&current->pi_lock);			\
>  		current->saved_state = current->__state;		\
>  		debug_rtlock_wait_set_state();				\
> +		trace_set_current_state(TASK_RTLOCK_WAIT);		\
>  		WRITE_ONCE(current->__state, TASK_RTLOCK_WAIT);		\
>  		raw_spin_unlock(&current->pi_lock);			\
>  	} while (0);
> @@ -291,6 +302,7 @@ struct user_event_mm;
>  		lockdep_assert_irqs_disabled();				\
>  		raw_spin_lock(&current->pi_lock);			\
>  		debug_rtlock_wait_restore_state();			\
> +		trace_set_current_state(current->saved_state);		\
>  		WRITE_ONCE(current->__state, current->saved_state);	\
>  		current->saved_state = TASK_RUNNING;			\
>  		raw_spin_unlock(&current->pi_lock);			\
> @@ -327,6 +339,10 @@ extern void io_schedule_finish(int token);
>  extern long io_schedule_timeout(long timeout);
>  extern void io_schedule(void);
>  
> +/* wrapper function to trace from this header file */
> +DECLARE_TRACEPOINT(sched_set_state_tp);
> +extern void __trace_set_current_state(int state_value);
> +
>  /**
>   * struct prev_cputime - snapshot of system and user cputime
>   * @utime: time spent in user mode
> diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
> index 9ea4c404bd4ef..90545125c9031 100644
> --- a/include/trace/events/sched.h
> +++ b/include/trace/events/sched.h
> @@ -824,6 +824,19 @@ DECLARE_TRACE(sched_compute_energy_tp,
>  		 unsigned long max_util, unsigned long busy_time),
>  	TP_ARGS(p, dst_cpu, energy, max_util, busy_time));
>  
> +DECLARE_TRACE(sched_entry_tp,
> +	TP_PROTO(bool preempt, unsigned long ip),
> +	TP_ARGS(preempt, ip));
> +
> +DECLARE_TRACE(sched_exit_tp,
> +	TP_PROTO(bool is_switch, unsigned long ip),
> +	TP_ARGS(is_switch, ip));
> +
> +DECLARE_TRACE_CONDITION(sched_set_state_tp,
> +	TP_PROTO(struct task_struct *tsk, int state),
> +	TP_ARGS(tsk, state),
> +	TP_CONDITION(!!(tsk->__state) != !!state));
> +
>  #endif /* _TRACE_SCHED_H */
>  
>  /* This part must be outside protection */
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 67189907214d3..5d36ccf565e94 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -491,6 +491,16 @@ sched_core_dequeue(struct rq *rq, struct task_struct *p, int flags) { }
>  
>  #endif /* CONFIG_SCHED_CORE */
>  
> +/* need a wrapper since we may need to trace from modules */
> +EXPORT_TRACEPOINT_SYMBOL(sched_set_state_tp);
> +
> +/* Call via the helper macro trace_set_current_state. */
> +void __trace_set_current_state(int state_value)
> +{
> +	trace_sched_set_state_tp(current, state_value);
> +}
> +EXPORT_SYMBOL(__trace_set_current_state);
> +
>  /*
>   * Serialization rules:
>   *
> @@ -5307,6 +5317,12 @@ asmlinkage __visible void schedule_tail(struct task_struct *prev)
>  	 */
>  
>  	finish_task_switch(prev);
> +	/*
> +	 * This is a special case: the newly created task has just
> +	 * switched the context for the first time. It is returning from
> +	 * schedule for the first time in this path.
> +	 */
> +	trace_sched_exit_tp(true, CALLER_ADDR0);
>  	preempt_enable();
>  
>  	if (current->set_child_tid)
> @@ -6650,12 +6666,15 @@ static void __sched notrace __schedule(int sched_mode)
>  	 * as a preemption by schedule_debug() and RCU.
>  	 */
>  	bool preempt = sched_mode > SM_NONE;
> +	bool is_switch = false;
>  	unsigned long *switch_count;
>  	unsigned long prev_state;
>  	struct rq_flags rf;
>  	struct rq *rq;
>  	int cpu;
>  
> +	trace_sched_entry_tp(preempt, CALLER_ADDR0);
> +
>  	cpu = smp_processor_id();
>  	rq = cpu_rq(cpu);
>  	prev = rq->curr;
> @@ -6723,7 +6742,8 @@ static void __sched notrace __schedule(int sched_mode)
>  	rq->last_seen_need_resched_ns = 0;
>  #endif
>  
> -	if (likely(prev != next)) {
> +	is_switch = prev != next;
> +	if (likely(is_switch)) {
>  		rq->nr_switches++;
>  		/*
>  		 * RCU users of rcu_dereference(rq->curr) may not see
> @@ -6768,6 +6788,7 @@ static void __sched notrace __schedule(int sched_mode)
>  		__balance_callbacks(rq);
>  		raw_spin_rq_unlock_irq(rq);
>  	}
> +	trace_sched_exit_tp(is_switch, CALLER_ADDR0);
>  }
>  
>  void __noreturn do_task_dead(void)
> diff --git a/tools/verification/rv/include/rv.h b/tools/verification/rv/include/rv.h
> index 770fd6da36107..0cab1037a98f7 100644
> --- a/tools/verification/rv/include/rv.h
> +++ b/tools/verification/rv/include/rv.h
> @@ -1,7 +1,7 @@
>  // SPDX-License-Identifier: GPL-2.0
>  
>  #define MAX_DESCRIPTION 1024
> -#define MAX_DA_NAME_LEN	24
> +#define MAX_DA_NAME_LEN	32
>  
>  struct monitor {
>  	char name[MAX_DA_NAME_LEN];
diff mbox series

Patch

diff --git a/include/linux/rv.h b/include/linux/rv.h
index 8883b41d88ec4..55d458be53a4c 100644
--- a/include/linux/rv.h
+++ b/include/linux/rv.h
@@ -7,7 +7,7 @@ 
 #ifndef _LINUX_RV_H
 #define _LINUX_RV_H
 
-#define MAX_DA_NAME_LEN	24
+#define MAX_DA_NAME_LEN	32
 
 #ifdef CONFIG_RV
 /*
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 9632e3318e0d6..45a61a0b97903 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -46,6 +46,7 @@ 
 #include <linux/rv.h>
 #include <linux/livepatch_sched.h>
 #include <linux/uidgid_types.h>
+#include <linux/tracepoint-defs.h>
 #include <asm/kmap_size.h>
 
 /* task_struct member predeclarations (sorted alphabetically): */
@@ -186,6 +187,12 @@  struct user_event_mm;
 # define debug_rtlock_wait_restore_state()	do { } while (0)
 #endif
 
+#define trace_set_current_state(state_value)                     \
+	do {                                                     \
+		if (tracepoint_enabled(sched_set_state_tp))      \
+			__trace_set_current_state(state_value); \
+	} while (0)
+
 /*
  * set_current_state() includes a barrier so that the write of current->__state
  * is correctly serialised wrt the caller's subsequent test of whether to
@@ -226,12 +233,14 @@  struct user_event_mm;
 #define __set_current_state(state_value)				\
 	do {								\
 		debug_normal_state_change((state_value));		\
+		trace_set_current_state(state_value);			\
 		WRITE_ONCE(current->__state, (state_value));		\
 	} while (0)
 
 #define set_current_state(state_value)					\
 	do {								\
 		debug_normal_state_change((state_value));		\
+		trace_set_current_state(state_value);			\
 		smp_store_mb(current->__state, (state_value));		\
 	} while (0)
 
@@ -247,6 +256,7 @@  struct user_event_mm;
 									\
 		raw_spin_lock_irqsave(&current->pi_lock, flags);	\
 		debug_special_state_change((state_value));		\
+		trace_set_current_state(state_value);			\
 		WRITE_ONCE(current->__state, (state_value));		\
 		raw_spin_unlock_irqrestore(&current->pi_lock, flags);	\
 	} while (0)
@@ -282,6 +292,7 @@  struct user_event_mm;
 		raw_spin_lock(&current->pi_lock);			\
 		current->saved_state = current->__state;		\
 		debug_rtlock_wait_set_state();				\
+		trace_set_current_state(TASK_RTLOCK_WAIT);		\
 		WRITE_ONCE(current->__state, TASK_RTLOCK_WAIT);		\
 		raw_spin_unlock(&current->pi_lock);			\
 	} while (0);
@@ -291,6 +302,7 @@  struct user_event_mm;
 		lockdep_assert_irqs_disabled();				\
 		raw_spin_lock(&current->pi_lock);			\
 		debug_rtlock_wait_restore_state();			\
+		trace_set_current_state(current->saved_state);		\
 		WRITE_ONCE(current->__state, current->saved_state);	\
 		current->saved_state = TASK_RUNNING;			\
 		raw_spin_unlock(&current->pi_lock);			\
@@ -327,6 +339,10 @@  extern void io_schedule_finish(int token);
 extern long io_schedule_timeout(long timeout);
 extern void io_schedule(void);
 
+/* wrapper function to trace from this header file */
+DECLARE_TRACEPOINT(sched_set_state_tp);
+extern void __trace_set_current_state(int state_value);
+
 /**
  * struct prev_cputime - snapshot of system and user cputime
  * @utime: time spent in user mode
diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
index 9ea4c404bd4ef..90545125c9031 100644
--- a/include/trace/events/sched.h
+++ b/include/trace/events/sched.h
@@ -824,6 +824,19 @@  DECLARE_TRACE(sched_compute_energy_tp,
 		 unsigned long max_util, unsigned long busy_time),
 	TP_ARGS(p, dst_cpu, energy, max_util, busy_time));
 
+DECLARE_TRACE(sched_entry_tp,
+	TP_PROTO(bool preempt, unsigned long ip),
+	TP_ARGS(preempt, ip));
+
+DECLARE_TRACE(sched_exit_tp,
+	TP_PROTO(bool is_switch, unsigned long ip),
+	TP_ARGS(is_switch, ip));
+
+DECLARE_TRACE_CONDITION(sched_set_state_tp,
+	TP_PROTO(struct task_struct *tsk, int state),
+	TP_ARGS(tsk, state),
+	TP_CONDITION(!!(tsk->__state) != !!state));
+
 #endif /* _TRACE_SCHED_H */
 
 /* This part must be outside protection */
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 67189907214d3..5d36ccf565e94 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -491,6 +491,16 @@  sched_core_dequeue(struct rq *rq, struct task_struct *p, int flags) { }
 
 #endif /* CONFIG_SCHED_CORE */
 
+/* need a wrapper since we may need to trace from modules */
+EXPORT_TRACEPOINT_SYMBOL(sched_set_state_tp);
+
+/* Call via the helper macro trace_set_current_state. */
+void __trace_set_current_state(int state_value)
+{
+	trace_sched_set_state_tp(current, state_value);
+}
+EXPORT_SYMBOL(__trace_set_current_state);
+
 /*
  * Serialization rules:
  *
@@ -5307,6 +5317,12 @@  asmlinkage __visible void schedule_tail(struct task_struct *prev)
 	 */
 
 	finish_task_switch(prev);
+	/*
+	 * This is a special case: the newly created task has just
+	 * switched the context for the first time. It is returning from
+	 * schedule for the first time in this path.
+	 */
+	trace_sched_exit_tp(true, CALLER_ADDR0);
 	preempt_enable();
 
 	if (current->set_child_tid)
@@ -6650,12 +6666,15 @@  static void __sched notrace __schedule(int sched_mode)
 	 * as a preemption by schedule_debug() and RCU.
 	 */
 	bool preempt = sched_mode > SM_NONE;
+	bool is_switch = false;
 	unsigned long *switch_count;
 	unsigned long prev_state;
 	struct rq_flags rf;
 	struct rq *rq;
 	int cpu;
 
+	trace_sched_entry_tp(preempt, CALLER_ADDR0);
+
 	cpu = smp_processor_id();
 	rq = cpu_rq(cpu);
 	prev = rq->curr;
@@ -6723,7 +6742,8 @@  static void __sched notrace __schedule(int sched_mode)
 	rq->last_seen_need_resched_ns = 0;
 #endif
 
-	if (likely(prev != next)) {
+	is_switch = prev != next;
+	if (likely(is_switch)) {
 		rq->nr_switches++;
 		/*
 		 * RCU users of rcu_dereference(rq->curr) may not see
@@ -6768,6 +6788,7 @@  static void __sched notrace __schedule(int sched_mode)
 		__balance_callbacks(rq);
 		raw_spin_rq_unlock_irq(rq);
 	}
+	trace_sched_exit_tp(is_switch, CALLER_ADDR0);
 }
 
 void __noreturn do_task_dead(void)
diff --git a/tools/verification/rv/include/rv.h b/tools/verification/rv/include/rv.h
index 770fd6da36107..0cab1037a98f7 100644
--- a/tools/verification/rv/include/rv.h
+++ b/tools/verification/rv/include/rv.h
@@ -1,7 +1,7 @@ 
 // SPDX-License-Identifier: GPL-2.0
 
 #define MAX_DESCRIPTION 1024
-#define MAX_DA_NAME_LEN	24
+#define MAX_DA_NAME_LEN	32
 
 struct monitor {
 	char name[MAX_DA_NAME_LEN];