sched: Add trace events for Proxy Execution (PE)

Message ID 20240202083338.1328060-1-metin.kaya@arm.com
State New
Headers
Series sched: Add trace events for Proxy Execution (PE) |

Commit Message

Metin Kaya Feb. 2, 2024, 8:33 a.m. UTC
  Add sched_[start, finish]_task_selection trace events to measure the
latency of PE patches in task selection.

Moreover, introduce trace events for interesting events in PE:
1. sched_pe_enqueue_sleeping_task: a task gets enqueued on wait queue of
   a sleeping task (mutex owner).
2. sched_pe_cross_remote_cpu: dependency chain crosses remote CPU.
3. sched_pe_task_is_migrating: mutex owner task migrates.

New trace events can be tested via this command:
$ perf trace \
  -e sched:sched_start_task_selection \
  -e sched:sched_finish_task_selection \
  -e sched:sched_pe_enqueue_sleeping_task \
  -e sched:sched_pe_cross_remote_cpu \
  -e sched:sched_pe_task_is_migrating

Notes:
1. These trace events are not intended to merge upstream. Instead, they
   are only for making PE tests easier and will be converted to trace
   points once PE patches hit upstream.
2. This patch is based on John's Proxy Execution v7 patch series (see
   the link below) which is also available at
   https://github.com/johnstultz-work/linux-dev/commits/proxy-exec-v7-6.7-rc6/.

Link: https://lore.kernel.org/linux-kernel/CANDhNCrHd+5twWVNqBAhVLfhMhkiO0KjxXBmwVgaCD4kAyFyWw@mail.gmail.com/

Signed-off-by: Metin Kaya <metin.kaya@arm.com>
CC: John Stultz <jstultz@google.com>
CC: Joel Fernandes <joelaf@google.com>
CC: Qais Yousef <qyousef@google.com>
CC: Ingo Molnar <mingo@redhat.com>
CC: Peter Zijlstra <peterz@infradead.org>
CC: Juri Lelli <juri.lelli@redhat.com>
CC: Vincent Guittot <vincent.guittot@linaro.org>
CC: Dietmar Eggemann <dietmar.eggemann@arm.com>
CC: Valentin Schneider <vschneid@redhat.com>
CC: Steven Rostedt <rostedt@goodmis.org>
CC: Masami Hiramatsu <mhiramat@kernel.org>
CC: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
CC: Ben Segall <bsegall@google.com>
CC: Zimuzo Ezeozue <zezeozue@google.com>
CC: Youssef Esmat <youssefesmat@google.com>
CC: Mel Gorman <mgorman@suse.de>
CC: Daniel Bristot de Oliveira <bristot@redhat.com>
CC: Will Deacon <will@kernel.org>
CC: Waiman Long <longman@redhat.com>
CC: Boqun Feng <boqun.feng@gmail.com>
CC: "Paul E. McKenney" <paulmck@kernel.org>
CC: Xuewen Yan <xuewen.yan94@gmail.com>
CC: K Prateek Nayak <kprateek.nayak@amd.com>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: kernel-team@android.com
CC: linux-trace-kernel@vger.kernel.org
---
 include/trace/events/sched.h | 138 +++++++++++++++++++++++++++++++++++
 kernel/sched/core.c          |  11 +++
 2 files changed, 149 insertions(+)
  

Comments

Steven Rostedt Feb. 21, 2024, 2:23 p.m. UTC | #1
On Fri,  2 Feb 2024 08:33:38 +0000
Metin Kaya <metin.kaya@arm.com> wrote:

> Add sched_[start, finish]_task_selection trace events to measure the
> latency of PE patches in task selection.
> 
> Moreover, introduce trace events for interesting events in PE:
> 1. sched_pe_enqueue_sleeping_task: a task gets enqueued on wait queue of
>    a sleeping task (mutex owner).
> 2. sched_pe_cross_remote_cpu: dependency chain crosses remote CPU.
> 3. sched_pe_task_is_migrating: mutex owner task migrates.
> 
> New trace events can be tested via this command:
> $ perf trace \
>   -e sched:sched_start_task_selection \
>   -e sched:sched_finish_task_selection \
>   -e sched:sched_pe_enqueue_sleeping_task \
>   -e sched:sched_pe_cross_remote_cpu \
>   -e sched:sched_pe_task_is_migrating
> 
> Notes:
> 1. These trace events are not intended to merge upstream. Instead, they
>    are only for making PE tests easier and will be converted to trace
>    points once PE patches hit upstream.

I wonder if the tracepoints should be added though? That is, not adding the
trace_events that show up in tracefs, but just the tracepoints so that bpf
or local modules could hook to them?

-- Steve


> 2. This patch is based on John's Proxy Execution v7 patch series (see
>    the link below) which is also available at
>    https://github.com/johnstultz-work/linux-dev/commits/proxy-exec-v7-6.7-rc6/.
> 
> Link: https://lore.kernel.org/linux-kernel/CANDhNCrHd+5twWVNqBAhVLfhMhkiO0KjxXBmwVgaCD4kAyFyWw@mail.gmail.com/
  
Metin Kaya Feb. 21, 2024, 2:24 p.m. UTC | #2
On 21/02/2024 2:23 pm, Steven Rostedt wrote:
> On Fri,  2 Feb 2024 08:33:38 +0000
> Metin Kaya <metin.kaya@arm.com> wrote:
> 
>> Add sched_[start, finish]_task_selection trace events to measure the
>> latency of PE patches in task selection.
>>
>> Moreover, introduce trace events for interesting events in PE:
>> 1. sched_pe_enqueue_sleeping_task: a task gets enqueued on wait queue of
>>     a sleeping task (mutex owner).
>> 2. sched_pe_cross_remote_cpu: dependency chain crosses remote CPU.
>> 3. sched_pe_task_is_migrating: mutex owner task migrates.
>>
>> New trace events can be tested via this command:
>> $ perf trace \
>>    -e sched:sched_start_task_selection \
>>    -e sched:sched_finish_task_selection \
>>    -e sched:sched_pe_enqueue_sleeping_task \
>>    -e sched:sched_pe_cross_remote_cpu \
>>    -e sched:sched_pe_task_is_migrating
>>
>> Notes:
>> 1. These trace events are not intended to merge upstream. Instead, they
>>     are only for making PE tests easier and will be converted to trace
>>     points once PE patches hit upstream.
> 
> I wonder if the tracepoints should be added though? That is, not adding the
> trace_events that show up in tracefs, but just the tracepoints so that bpf
> or local modules could hook to them?

Yep, the intention is providing necessary support for modules (e.g., 
https://github.com/ARM-software/lisa/blob/main/lisa/_assets/kmodules/lisa/tp.c). 


> 
> -- Steve
> 
> 
>> 2. This patch is based on John's Proxy Execution v7 patch series (see
>>     the link below) which is also available at
>>     https://github.com/johnstultz-work/linux-dev/commits/proxy-exec-v7-6.7-rc6/.
>>
>> Link: https://lore.kernel.org/linux-kernel/CANDhNCrHd+5twWVNqBAhVLfhMhkiO0KjxXBmwVgaCD4kAyFyWw@mail.gmail.com/
>
  

Patch

diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
index 6188ad0d9e0d..2b08509f3088 100644
--- a/include/trace/events/sched.h
+++ b/include/trace/events/sched.h
@@ -737,6 +737,144 @@  TRACE_EVENT(sched_wake_idle_without_ipi,
 	TP_printk("cpu=%d", __entry->cpu)
 );
 
+#ifdef CONFIG_SCHED_PROXY_EXEC
+/**
+ * sched_pe_enqueue_sleeping_task - called when a task is enqueued on wait
+ *				    queue of a sleeping task (mutex owner).
+ * @mutex_owner: pointer to struct task_struct
+ * @blocked:     pointer to struct task_struct
+ */
+TRACE_EVENT(sched_pe_enqueue_sleeping_task,
+
+	TP_PROTO(struct task_struct *mutex_owner, struct task_struct *blocked),
+
+	TP_ARGS(mutex_owner, blocked),
+
+	TP_STRUCT__entry(
+		__array(char,	owner_comm,	TASK_COMM_LEN	)
+		__field(pid_t,	owner_pid			)
+		__field(int,	owner_prio			)
+		__field(int,	owner_cpu			)
+		__array(char,	blocked_comm,	TASK_COMM_LEN	)
+		__field(pid_t,	blocked_pid			)
+		__field(int,	blocked_prio			)
+		__field(int,	blocked_cpu			)
+	),
+
+	TP_fast_assign(
+		strscpy(__entry->owner_comm, mutex_owner->comm, TASK_COMM_LEN);
+		__entry->owner_pid	= mutex_owner->pid;
+		__entry->owner_prio	= mutex_owner->prio; /* XXX SCHED_DEADLINE */
+		__entry->owner_cpu	= task_cpu(mutex_owner);
+
+		strscpy(__entry->blocked_comm, blocked->comm, TASK_COMM_LEN);
+		__entry->blocked_pid	= blocked->pid;
+		__entry->blocked_prio	= blocked->prio; /* XXX SCHED_DEADLINE */
+		__entry->blocked_cpu	= task_cpu(blocked);
+	),
+
+	TP_printk("task=%s pid=%d prio=%d cpu=%d blocked_on owner_task=%s owner_pid=%d owner_prio=%d owner_cpu=%d",
+		  __entry->blocked_comm, __entry->blocked_pid,
+		  __entry->blocked_prio, __entry->blocked_cpu,
+		  __entry->owner_comm, __entry->owner_pid,
+		  __entry->owner_prio, __entry->owner_cpu)
+);
+
+/**
+ * sched_pe_cross_remote_cpu - called when dependency chain crosses remote CPU
+ * @p: pointer to struct task_struct
+ */
+TRACE_EVENT(sched_pe_cross_remote_cpu,
+
+	TP_PROTO(struct task_struct *p),
+
+	TP_ARGS(p),
+
+	TP_STRUCT__entry(
+		__array(char,	comm,	TASK_COMM_LEN	)
+		__field(pid_t,	pid			)
+		__field(int,	prio			)
+		__field(int,	cpu			)
+	),
+
+	TP_fast_assign(
+		strscpy(__entry->comm, p->comm, TASK_COMM_LEN);
+		__entry->pid	= p->pid;
+		__entry->prio	= p->prio; /* XXX SCHED_DEADLINE */
+		__entry->cpu	= task_cpu(p);
+	),
+
+	TP_printk("comm=%s pid=%d prio=%d cpu=%d",
+		  __entry->comm, __entry->pid, __entry->prio, __entry->cpu)
+);
+
+/**
+ * sched_pe_task_is_migrating - called when mutex owner is in migrating state
+ * @p: pointer to struct task_struct
+ */
+TRACE_EVENT(sched_pe_task_is_migrating,
+
+	TP_PROTO(struct task_struct *p),
+
+	TP_ARGS(p),
+
+	TP_STRUCT__entry(
+		__array(char,	comm,	TASK_COMM_LEN	)
+		__field(pid_t,	pid			)
+		__field(int,	prio			)
+	),
+
+	TP_fast_assign(
+		strscpy(__entry->comm, p->comm, TASK_COMM_LEN);
+		__entry->pid		= p->pid;
+		__entry->prio		= p->prio; /* XXX SCHED_DEADLINE */
+	),
+
+	TP_printk("comm=%s pid=%d prio=%d",
+		  __entry->comm, __entry->pid, __entry->prio)
+);
+#endif /* CONFIG_SCHED_PROXY_EXEC */
+
+DECLARE_EVENT_CLASS(sched_task_selection_template,
+
+	TP_PROTO(int cpu),
+
+	TP_ARGS(cpu),
+
+	TP_STRUCT__entry(
+		__field(int,	cpu)
+	),
+
+	TP_fast_assign(
+		__entry->cpu	= cpu;
+	),
+
+	TP_printk("cpu=%d",
+		  __entry->cpu)
+);
+
+/**
+ * sched_start_task_selection - called before selecting next task in
+ *				__schedule()
+ * @cpu: The CPU which will run task selection operation.
+ */
+DEFINE_EVENT(sched_task_selection_template, sched_start_task_selection,
+
+	TP_PROTO(int cpu),
+
+	TP_ARGS(cpu));
+
+/**
+ * sched_finish_task_selection - called after selecting next task in
+ *				 __schedule()
+ * @cpu: The CPU which ran task selection operation.
+ */
+DEFINE_EVENT(sched_task_selection_template, sched_finish_task_selection,
+
+	TP_PROTO(int cpu),
+
+	TP_ARGS(cpu));
+
 /*
  * Following tracepoints are not exported in tracefs and provide hooking
  * mechanisms only for testing and debugging purposes.
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 30dfb6f14f2b..866809e52971 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7006,6 +7006,9 @@  static void proxy_enqueue_on_owner(struct rq *rq, struct task_struct *owner,
 	 */
 	if (!owner->on_rq) {
 		BUG_ON(!next->on_rq);
+
+		trace_sched_pe_enqueue_sleeping_task(owner, next);
+
 		deactivate_task(rq, next, DEQUEUE_SLEEP);
 		if (task_current_selected(rq, next)) {
 			put_prev_task(rq, next);
@@ -7100,6 +7103,9 @@  find_proxy_task(struct rq *rq, struct task_struct *next, struct rq_flags *rf)
 
 		if (task_cpu(owner) != cur_cpu) {
 			target_cpu = task_cpu(owner);
+
+			trace_sched_pe_cross_remote_cpu(owner);
+
 			/*
 			 * @owner can disappear, simply migrate to @target_cpu and leave that CPU
 			 * to sort things out.
@@ -7113,6 +7119,8 @@  find_proxy_task(struct rq *rq, struct task_struct *next, struct rq_flags *rf)
 		}
 
 		if (task_on_rq_migrating(owner)) {
+			trace_sched_pe_task_is_migrating(owner);
+
 			/*
 			 * One of the chain of mutex owners is currently migrating to this
 			 * CPU, but has not yet been enqueued because we are holding the
@@ -7335,6 +7343,8 @@  static void __sched notrace __schedule(unsigned int sched_mode)
 	}
 
 	prev_not_proxied = !prev->blocked_donor;
+
+	trace_sched_start_task_selection(cpu);
 pick_again:
 	next = pick_next_task(rq, rq_selected(rq), &rf);
 	rq_set_selected(rq, next);
@@ -7350,6 +7360,7 @@  static void __sched notrace __schedule(unsigned int sched_mode)
 		if (next == rq->idle && prev == rq->idle)
 			preserve_need_resched = true;
 	}
+	trace_sched_finish_task_selection(cpu);
 
 	if (!preserve_need_resched)
 		clear_tsk_need_resched(prev);