Messages in this thread Patch in this message | | | Date | Fri, 30 Jul 2021 15:12:56 +0200 | From | Sebastian Andrzej Siewior <> | Subject | [ANNOUNCE] v5.14-rc3-rt2 |
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Dear RT folks!
I'm pleased to announce the v5.14-rc3-rt2 patch set.
Changes since v5.14-rc3-rt1:
- To cope with SLUB based hackbench regression adaptive spinning has been introduced for all rtmutex based locks. This improves the hackbench time significantly.
Known issues - netconsole triggers WARN.
- The "Memory controller" (CONFIG_MEMCG) has been disabled.
The delta patch against v5.14-rc3-rt1 is appended below and can be found here:
https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.14/incr/patch-5.14-rc3-rt1-rt2.patch.xz
You can get this release via the git tree at:
git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git v5.14-rc3-rt2
The RT patch against v5.14-rc3 can be found here:
https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.14/older/patch-5.14-rc3-rt2.patch.xz
The split quilt queue is available at:
https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.14/older/patches-5.14-rc3-rt2.tar.xz
Sebastian
diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c index 58762a3970ed7..e347bbc12641d 100644 --- a/kernel/locking/rtmutex.c +++ b/kernel/locking/rtmutex.c @@ -1277,6 +1277,43 @@ static __always_inline void __rt_mutex_unlock(struct rt_mutex_base *lock) rt_mutex_slowunlock(lock); } +#ifdef CONFIG_SMP +/* + * Note that owner is a speculative pointer and dereferencing relies + * on rcu_read_lock() and the check against the lock owner. + */ +static bool rtmutex_adaptive_spinwait(struct rt_mutex_base *lock, + struct task_struct *owner) +{ + bool res = true; + + rcu_read_lock(); + for (;;) { + /* Owner changed. Trylock again */ + if (owner != rt_mutex_owner(lock)) + break; + /* + * Ensure that owner->on_cpu is dereferenced _after_ + * checking the above to be valid. + */ + barrier(); + if (!owner->on_cpu) { + res = false; + break; + } + cpu_relax(); + } + rcu_read_unlock(); + return res; +} +#else +static bool rtmutex_adaptive_spinwait(struct rt_mutex_base *lock, + struct task_struct *owner) +{ + return false; +} +#endif + #ifdef RT_MUTEX_BUILD_MUTEX /* * Functions required for: @@ -1361,6 +1398,7 @@ static int __sched rt_mutex_slowlock_block(struct rt_mutex_base *lock, struct rt_mutex_waiter *waiter) { struct rt_mutex *rtm = container_of(lock, struct rt_mutex, rtmutex); + struct task_struct *owner; int ret = 0; for (;;) { @@ -1383,9 +1421,14 @@ static int __sched rt_mutex_slowlock_block(struct rt_mutex_base *lock, break; } + if (waiter == rt_mutex_top_waiter(lock)) + owner = rt_mutex_owner(lock); + else + owner = NULL; raw_spin_unlock_irq(&lock->wait_lock); - schedule(); + if (!owner || !rtmutex_adaptive_spinwait(lock, owner)) + schedule(); raw_spin_lock_irq(&lock->wait_lock); set_current_state(state); @@ -1534,43 +1577,6 @@ static __always_inline int __rt_mutex_lock(struct rt_mutex_base *lock, * Functions required for spin/rw_lock substitution on RT kernels */ -#ifdef CONFIG_SMP -/* - * Note that owner is a speculative pointer and dereferencing relies - * on rcu_read_lock() and the check against the lock owner. - */ -static bool rtlock_adaptive_spinwait(struct rt_mutex_base *lock, - struct task_struct *owner) -{ - bool res = true; - - rcu_read_lock(); - for (;;) { - /* Owner changed. Trylock again */ - if (owner != rt_mutex_owner(lock)) - break; - /* - * Ensure that owner->on_cpu is dereferenced _after_ - * checking the above to be valid. - */ - barrier(); - if (!owner->on_cpu) { - res = false; - break; - } - cpu_relax(); - } - rcu_read_unlock(); - return res; -} -#else -static bool rtlock_adaptive_spinwait(struct rt_mutex_base *lock, - struct task_struct *owner) -{ - return false; -} -#endif - /** * rtlock_slowlock_locked - Slow path lock acquisition for RT locks * @lock: The underlying rt mutex @@ -1603,7 +1609,7 @@ static void __sched rtlock_slowlock_locked(struct rt_mutex_base *lock) owner = NULL; raw_spin_unlock_irq(&lock->wait_lock); - if (!owner || !rtlock_adaptive_spinwait(lock, owner)) + if (!owner || !rtmutex_adaptive_spinwait(lock, owner)) schedule_rtlock(); raw_spin_lock_irq(&lock->wait_lock); diff --git a/localversion-rt b/localversion-rt index 6f206be67cd28..c3054d08a1129 100644 --- a/localversion-rt +++ b/localversion-rt @@ -1 +1 @@ --rt1 +-rt2
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