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Date: Mon, 11 Mar 2024 11:55:02 +0800
From: Zqiang <qiang.zhang1211@...il.com>
To: paulmck@...nel.org,
frederic@...nel.org,
joel@...lfernandes.org,
neeraj.upadhyay@...nel.org
Cc: qiang.zhang1211@...il.com,
rcu@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH] rcu-tasks: Avoid rtp_irq_work triggering when the rcu-tasks GP is ongoing
This commit generate rcu_task_gp_in_progress() to check whether
the rcu-tasks GP is ongoing, if is ongoing, avoid trigger
rtp_irq_work to wakeup rcu tasks kthreads in call_rcu_tasks_generic().
The test results are as follows:
echo call_rcu_tasks_iw_wakeup > /sys/kernel/debug/tracing/set_ftrace_filter
echo 1 > /sys/kernel/debug/tracing/function_profile_enabled
insmod rcutorture.ko torture_type=tasks-tracing fwd_progress=4
sleep 600
rmmod rcutorture.ko
echo 0 > /sys/kernel/debug/tracing/function_profile_enabled
echo > /sys/kernel/debug/tracing/set_ftrace_filter
head /sys/kernel/debug/tracing/trace_stat/function*
original: 56376 apply patch: 33521
Signed-off-by: Zqiang <qiang.zhang1211@...il.com>
---
original:
==> /sys/kernel/debug/tracing/trace_stat/function0 <==
Function Hit Time Avg s^2
-------- --- ---- --- ---
call_rcu_tasks_iw_wakeup 13217 19292.52 us 1.459 us 8.834 us
==> /sys/kernel/debug/tracing/trace_stat/function1 <==
Function Hit Time Avg s^2
-------- --- ---- --- ---
call_rcu_tasks_iw_wakeup 15146 22377.01 us 1.477 us 22.873 us
==> /sys/kernel/debug/tracing/trace_stat/function2 <==
Function Hit Time Avg s^2
-------- --- ---- --- ---
call_rcu_tasks_iw_wakeup 12561 18125.76 us 1.443 us 6.372 us
==> /sys/kernel/debug/tracing/trace_stat/function3 <==
Function Hit Time Avg s^2
-------- --- ---- --- ---
call_rcu_tasks_iw_wakeup 15452 21770.57 us 1.408 us 6.710 us
apply patch:
==> /sys/kernel/debug/tracing/trace_stat/function0 <==
Function Hit Time Avg s^2
-------- --- ---- --- ---
call_rcu_tasks_iw_wakeup 8334 15121.13 us 1.814 us 4.457 us
==> /sys/kernel/debug/tracing/trace_stat/function1 <==
Function Hit Time Avg s^2
-------- --- ---- --- ---
call_rcu_tasks_iw_wakeup 8355 15760.51 us 1.886 us 14.775 us
==> /sys/kernel/debug/tracing/trace_stat/function2 <==
Function Hit Time Avg s^2
-------- --- ---- --- ---
call_rcu_tasks_iw_wakeup 7219 14194.27 us 1.966 us 42.440 us
==> /sys/kernel/debug/tracing/trace_stat/function3 <==
Function Hit Time Avg s^2
-------- --- ---- --- ---
call_rcu_tasks_iw_wakeup 9613 19850.04 us 2.064 us 91.023 us
kernel/rcu/tasks.h | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
index 147b5945d67a..36c7e1d441d0 100644
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -317,6 +317,11 @@ static void call_rcu_tasks_iw_wakeup(struct irq_work *iwp)
rcuwait_wake_up(&rtp->cbs_wait);
}
+static int rcu_task_gp_in_progress(struct rcu_tasks *rtp)
+{
+ return rcu_seq_state(rcu_seq_current(&rtp->tasks_gp_seq));
+}
+
// Enqueue a callback for the specified flavor of Tasks RCU.
static void call_rcu_tasks_generic(struct rcu_head *rhp, rcu_callback_t func,
struct rcu_tasks *rtp)
@@ -375,7 +380,8 @@ static void call_rcu_tasks_generic(struct rcu_head *rhp, rcu_callback_t func,
}
rcu_read_unlock();
/* We can't create the thread unless interrupts are enabled. */
- if (needwake && READ_ONCE(rtp->kthread_ptr))
+ if (needwake && READ_ONCE(rtp->kthread_ptr) &&
+ !rcu_task_gp_in_progress(rtp))
irq_work_queue(&rtpcp->rtp_irq_work);
}
--
2.17.1
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