From nobody Sun Feb 8 06:49:12 2026 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 53C1D82D98; Sat, 8 Mar 2025 00:08:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741392497; cv=none; b=KC+Zl1ya9jyMDmFOOTpadRqjIVSUoWoD/TO/vrw5Vpn8c5FLCRAKC3aEe3jvddvxZ8yHBfVPNkknO0FGou57COJ6mWXwUFxUElP6a0pdzMhfzz80+UwqC+XMlYwVjuYeOM50+Vrzos33PhJtF+vu/cIBCD23tGMOR3HGUjfUVBs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741392497; c=relaxed/simple; bh=PlW28mI10vPuIAfVg6KF77ZaO0yao6nzu3NXETomr3s=; h=Date:From:To:Subject:Cc:In-Reply-To:References:MIME-Version: Message-ID:Content-Type; b=uiEuiIuZpPU7ok6WS+fPnS8AJsdyfctKZYytYWilK78IJ5WdaN6RQM+OpJLqKNwNIjhnsyRXMQSAkxO7LHyN6Vl+GtqDHx26OqaHFFCtb4K0ZUGb6ZF/Xp3F0SP62WzrvhUNeRuP69BZ0fkj0C9T5v+oer0DWWG0J5lq0qctwI8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=TcCXxPXK; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=9iCQkvyO; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="TcCXxPXK"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="9iCQkvyO" Date: Sat, 08 Mar 2025 00:08:07 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1741392493; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=niRO7dlC9J1/iMo3kUhkJuAbkTO4PuOFj14SweFrT0I=; b=TcCXxPXKdEv5PLMm6OhkHYGfgQTikXdN5ZtnBXsxlkZUterYYt8ZWgKf0ciZzc+NBYb8gV r6skOTFeyDo3BhWlWni0PgKKng9ibNudifY7I7+uC0nM0VAh02g7XyrPBXq5uNeq86bInW FdasTSeuaxKW+JLBzGH7OKYK5dYHuOLyJdcUwL6hSsAuA0Het5KL1eW8zngndQS7lwX3rC tp+qnnZtAiIA0IpZQj2FFnR+zg+Fh14cANC6LaFvGv7J34UG571Emt+4HYcgegkwE6Mix+ qcVgSsrwcfgxJyos5yvjno/IRATmqcYkbySrMw2YKQFlEe4AcAVlohly6yGYiw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1741392493; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=niRO7dlC9J1/iMo3kUhkJuAbkTO4PuOFj14SweFrT0I=; b=9iCQkvyOgVdni1GwP3uJIeluwd6guEgQsBIfheenCbXhizpXqq6sNdd42ZnLCO5O3lm4c6 yzqMCq4s/u/T3/Ag== From: "tip-bot2 for Waiman Long" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: locking/core] locking/lock_events: Add locking events for rtmutex slow paths Cc: Waiman Long , Boqun Feng , Ingo Molnar , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20250307232717.1759087-4-boqun.feng@gmail.com> References: <20250307232717.1759087-4-boqun.feng@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-ID: <174139249256.14745.17990965280661455686.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Precedence: bulk Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable The following commit has been merged into the locking/core branch of tip: Commit-ID: b76b44fb656100fcd8482d9102d35d1b6a5129e9 Gitweb: https://git.kernel.org/tip/b76b44fb656100fcd8482d9102d35d1b6= a5129e9 Author: Waiman Long AuthorDate: Fri, 07 Mar 2025 15:26:53 -08:00 Committer: Ingo Molnar CommitterDate: Sat, 08 Mar 2025 00:55:03 +01:00 locking/lock_events: Add locking events for rtmutex slow paths Add locking events for rtlock_slowlock() and rt_mutex_slowlock() for profiling the slow path behavior of rt_spin_lock() and rt_mutex_lock(). Signed-off-by: Waiman Long Signed-off-by: Boqun Feng Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20250307232717.1759087-4-boqun.feng@gmail.c= om --- kernel/locking/lock_events_list.h | 21 +++++++++++++++++++++ kernel/locking/rtmutex.c | 29 ++++++++++++++++++++++++----- 2 files changed, 45 insertions(+), 5 deletions(-) diff --git a/kernel/locking/lock_events_list.h b/kernel/locking/lock_events= _list.h index 97fb6f3..80b11f1 100644 --- a/kernel/locking/lock_events_list.h +++ b/kernel/locking/lock_events_list.h @@ -67,3 +67,24 @@ LOCK_EVENT(rwsem_rlock_handoff) /* # of read lock handof= fs */ LOCK_EVENT(rwsem_wlock) /* # of write locks acquired */ LOCK_EVENT(rwsem_wlock_fail) /* # of failed write lock acquisitions */ LOCK_EVENT(rwsem_wlock_handoff) /* # of write lock handoffs */ + +/* + * Locking events for rtlock_slowlock() + */ +LOCK_EVENT(rtlock_slowlock) /* # of rtlock_slowlock() calls */ +LOCK_EVENT(rtlock_slow_acq1) /* # of locks acquired after wait_lock */ +LOCK_EVENT(rtlock_slow_acq2) /* # of locks acquired in for loop */ +LOCK_EVENT(rtlock_slow_sleep) /* # of sleeps */ +LOCK_EVENT(rtlock_slow_wake) /* # of wakeup's */ + +/* + * Locking events for rt_mutex_slowlock() + */ +LOCK_EVENT(rtmutex_slowlock) /* # of rt_mutex_slowlock() calls */ +LOCK_EVENT(rtmutex_slow_block) /* # of rt_mutex_slowlock_block() calls */ +LOCK_EVENT(rtmutex_slow_acq1) /* # of locks acquired after wait_lock */ +LOCK_EVENT(rtmutex_slow_acq2) /* # of locks acquired at the end */ +LOCK_EVENT(rtmutex_slow_acq3) /* # of locks acquired in *block() */ +LOCK_EVENT(rtmutex_slow_sleep) /* # of sleeps */ +LOCK_EVENT(rtmutex_slow_wake) /* # of wakeup's */ +LOCK_EVENT(rtmutex_deadlock) /* # of rt_mutex_handle_deadlock()'s */ diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c index 4a8df18..c80902e 100644 --- a/kernel/locking/rtmutex.c +++ b/kernel/locking/rtmutex.c @@ -27,6 +27,7 @@ #include =20 #include "rtmutex_common.h" +#include "lock_events.h" =20 #ifndef WW_RT # define build_ww_mutex() (false) @@ -1612,10 +1613,13 @@ static int __sched rt_mutex_slowlock_block(struct r= t_mutex_base *lock, struct task_struct *owner; int ret =3D 0; =20 + lockevent_inc(rtmutex_slow_block); for (;;) { /* Try to acquire the lock: */ - if (try_to_take_rt_mutex(lock, current, waiter)) + if (try_to_take_rt_mutex(lock, current, waiter)) { + lockevent_inc(rtmutex_slow_acq3); break; + } =20 if (timeout && !timeout->task) { ret =3D -ETIMEDOUT; @@ -1638,8 +1642,10 @@ static int __sched rt_mutex_slowlock_block(struct rt= _mutex_base *lock, owner =3D NULL; raw_spin_unlock_irq_wake(&lock->wait_lock, wake_q); =20 - if (!owner || !rtmutex_spin_on_owner(lock, waiter, owner)) + if (!owner || !rtmutex_spin_on_owner(lock, waiter, owner)) { + lockevent_inc(rtmutex_slow_sleep); rt_mutex_schedule(); + } =20 raw_spin_lock_irq(&lock->wait_lock); set_current_state(state); @@ -1694,6 +1700,7 @@ static int __sched __rt_mutex_slowlock(struct rt_mute= x_base *lock, int ret; =20 lockdep_assert_held(&lock->wait_lock); + lockevent_inc(rtmutex_slowlock); =20 /* Try to acquire the lock again: */ if (try_to_take_rt_mutex(lock, current, NULL)) { @@ -1701,6 +1708,7 @@ static int __sched __rt_mutex_slowlock(struct rt_mute= x_base *lock, __ww_mutex_check_waiters(rtm, ww_ctx, wake_q); ww_mutex_lock_acquired(ww, ww_ctx); } + lockevent_inc(rtmutex_slow_acq1); return 0; } =20 @@ -1719,10 +1727,12 @@ static int __sched __rt_mutex_slowlock(struct rt_mu= tex_base *lock, __ww_mutex_check_waiters(rtm, ww_ctx, wake_q); ww_mutex_lock_acquired(ww, ww_ctx); } + lockevent_inc(rtmutex_slow_acq2); } else { __set_current_state(TASK_RUNNING); remove_waiter(lock, waiter); rt_mutex_handle_deadlock(ret, chwalk, lock, waiter); + lockevent_inc(rtmutex_deadlock); } =20 /* @@ -1751,6 +1761,7 @@ static inline int __rt_mutex_slowlock_locked(struct r= t_mutex_base *lock, &waiter, wake_q); =20 debug_rt_mutex_free_waiter(&waiter); + lockevent_cond_inc(rtmutex_slow_wake, !wake_q_empty(wake_q)); return ret; } =20 @@ -1823,9 +1834,12 @@ static void __sched rtlock_slowlock_locked(struct rt= _mutex_base *lock, struct task_struct *owner; =20 lockdep_assert_held(&lock->wait_lock); + lockevent_inc(rtlock_slowlock); =20 - if (try_to_take_rt_mutex(lock, current, NULL)) + if (try_to_take_rt_mutex(lock, current, NULL)) { + lockevent_inc(rtlock_slow_acq1); return; + } =20 rt_mutex_init_rtlock_waiter(&waiter); =20 @@ -1838,8 +1852,10 @@ static void __sched rtlock_slowlock_locked(struct rt= _mutex_base *lock, =20 for (;;) { /* Try to acquire the lock again */ - if (try_to_take_rt_mutex(lock, current, &waiter)) + if (try_to_take_rt_mutex(lock, current, &waiter)) { + lockevent_inc(rtlock_slow_acq2); break; + } =20 if (&waiter =3D=3D rt_mutex_top_waiter(lock)) owner =3D rt_mutex_owner(lock); @@ -1847,8 +1863,10 @@ static void __sched rtlock_slowlock_locked(struct rt= _mutex_base *lock, owner =3D NULL; raw_spin_unlock_irq_wake(&lock->wait_lock, wake_q); =20 - if (!owner || !rtmutex_spin_on_owner(lock, &waiter, owner)) + if (!owner || !rtmutex_spin_on_owner(lock, &waiter, owner)) { + lockevent_inc(rtlock_slow_sleep); schedule_rtlock(); + } =20 raw_spin_lock_irq(&lock->wait_lock); set_current_state(TASK_RTLOCK_WAIT); @@ -1865,6 +1883,7 @@ static void __sched rtlock_slowlock_locked(struct rt_= mutex_base *lock, debug_rt_mutex_free_waiter(&waiter); =20 trace_contention_end(lock, 0); + lockevent_cond_inc(rtlock_slow_wake, !wake_q_empty(wake_q)); } =20 static __always_inline void __sched rtlock_slowlock(struct rt_mutex_base *= lock)