From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753461Ab3LQMqT (ORCPT ); Tue, 17 Dec 2013 07:46:19 -0500 Received: from merlin.infradead.org ([205.233.59.134]:41682 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753421Ab3LQMqO (ORCPT ); Tue, 17 Dec 2013 07:46:14 -0500 Message-Id: <20131217123353.045465166@infradead.org> User-Agent: quilt/0.60-1 Date: Tue, 17 Dec 2013 13:27:27 +0100 From: Peter Zijlstra To: tglx@linutronix.de, mingo@redhat.com, rostedt@goodmis.org, oleg@redhat.com, fweisbec@gmail.com, darren@dvhart.com, johan.eker@ericsson.com, p.faure@akatech.ch, linux-kernel@vger.kernel.org, claudio@evidence.eu.com, michael@amarulasolutions.com, fchecconi@gmail.com, tommaso.cucinotta@sssup.it, juri.lelli@gmail.com, nicola.manica@disi.unitn.it, luca.abeni@unitn.it, dhaval.giani@gmail.com, hgu1972@gmail.com, paulmck@linux.vnet.ibm.com, raistlin@linux.it, insop.song@gmail.com, liming.wang@windriver.com, jkacur@redhat.com Cc: Peter Zijlstra Subject: [PATCH 07/13] rtmutex: Turn the plist into an rb-tree References: <20131217122720.950475833@infradead.org> Content-Disposition: inline; filename=0008-rtmutex-Turn-the-plist-into-an-rb-tree.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Turn the pi-chains from plist to rb-tree, in the rt_mutex code, and provide a proper comparison function for -deadline and -priority tasks. This is done mainly because: - classical prio field of the plist is just an int, which might not be enough for representing a deadline; - manipulating such a list would become O(nr_deadline_tasks), which might be to much, as the number of -deadline task increases. Therefore, an rb-tree is used, and tasks are queued in it according to the following logic: - among two -priority (i.e., SCHED_BATCH/OTHER/RR/FIFO) tasks, the one with the higher (lower, actually!) prio wins; - among a -priority and a -deadline task, the latter always wins; - among two -deadline tasks, the one with the earliest deadline wins. Queueing and dequeueing functions are changed accordingly, for both the list of a task's pi-waiters and the list of tasks blocked on a pi-lock. Cc: nicola.manica@disi.unitn.it Cc: darren@dvhart.com Cc: oleg@redhat.com Cc: dhaval.giani@gmail.com Cc: paulmck@linux.vnet.ibm.com Cc: fchecconi@gmail.com Cc: fweisbec@gmail.com Cc: harald.gustafsson@ericsson.com Cc: hgu1972@gmail.com Cc: insop.song@gmail.com Cc: p.faure@akatech.ch Cc: jkacur@redhat.com Cc: rostedt@goodmis.org Cc: johan.eker@ericsson.com Cc: tglx@linutronix.de Cc: liming.wang@windriver.com Cc: tommaso.cucinotta@sssup.it Cc: luca.abeni@unitn.it Cc: vincent.guittot@linaro.org Cc: michael@amarulasolutions.com Cc: bruce.ashfield@windriver.com Cc: mingo@redhat.com Cc: claudio@evidence.eu.com Signed-off-by: Peter Zijlstra Signed-off-by: Dario Faggioli Signed-off-by: Juri Lelli Signed-off-by: Peter Zijlstra --- include/linux/init_task.h | 10 ++ include/linux/rtmutex.h | 18 +--- include/linux/sched.h | 4 - kernel/fork.c | 3 kernel/futex.c | 2 kernel/locking/rtmutex-debug.c | 8 -- kernel/locking/rtmutex.c | 151 ++++++++++++++++++++++++++++++++-------- kernel/locking/rtmutex_common.h | 22 ++--- kernel/sched/core.c | 4 - 9 files changed, 157 insertions(+), 65 deletions(-) --- a/include/linux/init_task.h +++ b/include/linux/init_task.h @@ -11,6 +11,7 @@ #include #include #include +#include #include #include @@ -154,6 +155,14 @@ extern struct task_group root_task_group #define INIT_TASK_COMM "swapper" +#ifdef CONFIG_RT_MUTEXES +# define INIT_RT_MUTEXES(tsk) \ + .pi_waiters = RB_ROOT, \ + .pi_waiters_leftmost = NULL, +#else +# define INIT_RT_MUTEXES(tsk) +#endif + /* * INIT_TASK is used to set up the first task table, touch at * your own risk!. Base=0, limit=0x1fffff (=2MB) @@ -221,6 +230,7 @@ extern struct task_group root_task_group INIT_TRACE_RECURSION \ INIT_TASK_RCU_PREEMPT(tsk) \ INIT_CPUSET_SEQ(tsk) \ + INIT_RT_MUTEXES(tsk) \ INIT_VTIME(tsk) \ } --- a/include/linux/rtmutex.h +++ b/include/linux/rtmutex.h @@ -13,7 +13,7 @@ #define __LINUX_RT_MUTEX_H #include -#include +#include #include extern int max_lock_depth; /* for sysctl */ @@ -22,12 +22,14 @@ extern int max_lock_depth; /* for sysctl * The rt_mutex structure * * @wait_lock: spinlock to protect the structure - * @wait_list: pilist head to enqueue waiters in priority order + * @waiters: rbtree root to enqueue waiters in priority order + * @waiters_leftmost: top waiter * @owner: the mutex owner */ struct rt_mutex { raw_spinlock_t wait_lock; - struct plist_head wait_list; + struct rb_root waiters; + struct rb_node *waiters_leftmost; struct task_struct *owner; #ifdef CONFIG_DEBUG_RT_MUTEXES int save_state; @@ -66,7 +68,7 @@ struct hrtimer_sleeper; #define __RT_MUTEX_INITIALIZER(mutexname) \ { .wait_lock = __RAW_SPIN_LOCK_UNLOCKED(mutexname.wait_lock) \ - , .wait_list = PLIST_HEAD_INIT(mutexname.wait_list) \ + , .waiters = RB_ROOT \ , .owner = NULL \ __DEBUG_RT_MUTEX_INITIALIZER(mutexname)} @@ -98,12 +100,4 @@ extern int rt_mutex_trylock(struct rt_mu extern void rt_mutex_unlock(struct rt_mutex *lock); -#ifdef CONFIG_RT_MUTEXES -# define INIT_RT_MUTEXES(tsk) \ - .pi_waiters = PLIST_HEAD_INIT(tsk.pi_waiters), \ - INIT_RT_MUTEX_DEBUG(tsk) -#else -# define INIT_RT_MUTEXES(tsk) -#endif - #endif --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -16,6 +16,7 @@ struct sched_param { #include #include #include +#include #include #include #include @@ -1346,7 +1347,8 @@ struct task_struct { #ifdef CONFIG_RT_MUTEXES /* PI waiters blocked on a rt_mutex held by this task */ - struct plist_head pi_waiters; + struct rb_root pi_waiters; + struct rb_node *pi_waiters_leftmost; /* Deadlock detection and priority inheritance handling */ struct rt_mutex_waiter *pi_blocked_on; #endif --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1086,7 +1086,8 @@ static void rt_mutex_init_task(struct ta { raw_spin_lock_init(&p->pi_lock); #ifdef CONFIG_RT_MUTEXES - plist_head_init(&p->pi_waiters); + p->pi_waiters = RB_ROOT; + p->pi_waiters_leftmost = NULL; p->pi_blocked_on = NULL; #endif } --- a/kernel/futex.c +++ b/kernel/futex.c @@ -2315,6 +2315,8 @@ static int futex_wait_requeue_pi(u32 __u * code while we sleep on uaddr. */ debug_rt_mutex_init_waiter(&rt_waiter); + RB_CLEAR_NODE(&rt_waiter.pi_tree_entry); + RB_CLEAR_NODE(&rt_waiter.tree_entry); rt_waiter.task = NULL; ret = get_futex_key(uaddr2, flags & FLAGS_SHARED, &key2, VERIFY_WRITE); --- a/kernel/locking/rtmutex-debug.c +++ b/kernel/locking/rtmutex-debug.c @@ -24,7 +24,7 @@ #include #include #include -#include +#include #include #include @@ -57,7 +57,7 @@ static void printk_lock(struct rt_mutex void rt_mutex_debug_task_free(struct task_struct *task) { - DEBUG_LOCKS_WARN_ON(!plist_head_empty(&task->pi_waiters)); + DEBUG_LOCKS_WARN_ON(!RB_EMPTY_ROOT(&task->pi_waiters)); DEBUG_LOCKS_WARN_ON(task->pi_blocked_on); } @@ -154,16 +154,12 @@ void debug_rt_mutex_proxy_unlock(struct void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter) { memset(waiter, 0x11, sizeof(*waiter)); - plist_node_init(&waiter->list_entry, MAX_PRIO); - plist_node_init(&waiter->pi_list_entry, MAX_PRIO); waiter->deadlock_task_pid = NULL; } void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter) { put_pid(waiter->deadlock_task_pid); - DEBUG_LOCKS_WARN_ON(!plist_node_empty(&waiter->list_entry)); - DEBUG_LOCKS_WARN_ON(!plist_node_empty(&waiter->pi_list_entry)); memset(waiter, 0x22, sizeof(*waiter)); } --- a/kernel/locking/rtmutex.c +++ b/kernel/locking/rtmutex.c @@ -14,6 +14,7 @@ #include #include #include +#include #include #include "rtmutex_common.h" @@ -91,10 +92,104 @@ static inline void mark_rt_mutex_waiters } #endif +static inline int +rt_mutex_waiter_less(struct rt_mutex_waiter *left, + struct rt_mutex_waiter *right) +{ + if (left->task->prio < right->task->prio) + return 1; + + /* + * If both tasks are dl_task(), we check their deadlines. + */ + if (dl_prio(left->task->prio) && dl_prio(right->task->prio)) + return (left->task->dl.deadline < right->task->dl.deadline); + + return 0; +} + +static void +rt_mutex_enqueue(struct rt_mutex *lock, struct rt_mutex_waiter *waiter) +{ + struct rb_node **link = &lock->waiters.rb_node; + struct rb_node *parent = NULL; + struct rt_mutex_waiter *entry; + int leftmost = 1; + + while (*link) { + parent = *link; + entry = rb_entry(parent, struct rt_mutex_waiter, tree_entry); + if (rt_mutex_waiter_less(waiter, entry)) { + link = &parent->rb_left; + } else { + link = &parent->rb_right; + leftmost = 0; + } + } + + if (leftmost) + lock->waiters_leftmost = &waiter->tree_entry; + + rb_link_node(&waiter->tree_entry, parent, link); + rb_insert_color(&waiter->tree_entry, &lock->waiters); +} + +static void +rt_mutex_dequeue(struct rt_mutex *lock, struct rt_mutex_waiter *waiter) +{ + if (RB_EMPTY_NODE(&waiter->tree_entry)) + return; + + if (lock->waiters_leftmost == &waiter->tree_entry) + lock->waiters_leftmost = rb_next(&waiter->tree_entry); + + rb_erase(&waiter->tree_entry, &lock->waiters); + RB_CLEAR_NODE(&waiter->tree_entry); +} + +static void +rt_mutex_enqueue_pi(struct task_struct *task, struct rt_mutex_waiter *waiter) +{ + struct rb_node **link = &task->pi_waiters.rb_node; + struct rb_node *parent = NULL; + struct rt_mutex_waiter *entry; + int leftmost = 1; + + while (*link) { + parent = *link; + entry = rb_entry(parent, struct rt_mutex_waiter, pi_tree_entry); + if (rt_mutex_waiter_less(waiter, entry)) { + link = &parent->rb_left; + } else { + link = &parent->rb_right; + leftmost = 0; + } + } + + if (leftmost) + task->pi_waiters_leftmost = &waiter->pi_tree_entry; + + rb_link_node(&waiter->pi_tree_entry, parent, link); + rb_insert_color(&waiter->pi_tree_entry, &task->pi_waiters); +} + +static void +rt_mutex_dequeue_pi(struct task_struct *task, struct rt_mutex_waiter *waiter) +{ + if (RB_EMPTY_NODE(&waiter->pi_tree_entry)) + return; + + if (task->pi_waiters_leftmost == &waiter->pi_tree_entry) + task->pi_waiters_leftmost = rb_next(&waiter->pi_tree_entry); + + rb_erase(&waiter->pi_tree_entry, &task->pi_waiters); + RB_CLEAR_NODE(&waiter->pi_tree_entry); +} + /* - * Calculate task priority from the waiter list priority + * Calculate task priority from the waiter tree priority * - * Return task->normal_prio when the waiter list is empty or when + * Return task->normal_prio when the waiter tree is empty or when * the waiter is not allowed to do priority boosting */ int rt_mutex_getprio(struct task_struct *task) @@ -102,7 +197,7 @@ int rt_mutex_getprio(struct task_struct if (likely(!task_has_pi_waiters(task))) return task->normal_prio; - return min(task_top_pi_waiter(task)->pi_list_entry.prio, + return min(task_top_pi_waiter(task)->task->prio, task->normal_prio); } @@ -233,7 +328,7 @@ static int rt_mutex_adjust_prio_chain(st * When deadlock detection is off then we check, if further * priority adjustment is necessary. */ - if (!detect_deadlock && waiter->list_entry.prio == task->prio) + if (!detect_deadlock && waiter->task->prio == task->prio) goto out_unlock_pi; lock = waiter->lock; @@ -254,9 +349,9 @@ static int rt_mutex_adjust_prio_chain(st top_waiter = rt_mutex_top_waiter(lock); /* Requeue the waiter */ - plist_del(&waiter->list_entry, &lock->wait_list); - waiter->list_entry.prio = task->prio; - plist_add(&waiter->list_entry, &lock->wait_list); + rt_mutex_dequeue(lock, waiter); + waiter->task->prio = task->prio; + rt_mutex_enqueue(lock, waiter); /* Release the task */ raw_spin_unlock_irqrestore(&task->pi_lock, flags); @@ -280,17 +375,15 @@ static int rt_mutex_adjust_prio_chain(st if (waiter == rt_mutex_top_waiter(lock)) { /* Boost the owner */ - plist_del(&top_waiter->pi_list_entry, &task->pi_waiters); - waiter->pi_list_entry.prio = waiter->list_entry.prio; - plist_add(&waiter->pi_list_entry, &task->pi_waiters); + rt_mutex_dequeue_pi(task, top_waiter); + rt_mutex_enqueue_pi(task, waiter); __rt_mutex_adjust_prio(task); } else if (top_waiter == waiter) { /* Deboost the owner */ - plist_del(&waiter->pi_list_entry, &task->pi_waiters); + rt_mutex_dequeue_pi(task, waiter); waiter = rt_mutex_top_waiter(lock); - waiter->pi_list_entry.prio = waiter->list_entry.prio; - plist_add(&waiter->pi_list_entry, &task->pi_waiters); + rt_mutex_enqueue_pi(task, waiter); __rt_mutex_adjust_prio(task); } @@ -355,7 +448,7 @@ static int try_to_take_rt_mutex(struct r * 3) it is top waiter */ if (rt_mutex_has_waiters(lock)) { - if (task->prio >= rt_mutex_top_waiter(lock)->list_entry.prio) { + if (task->prio >= rt_mutex_top_waiter(lock)->task->prio) { if (!waiter || waiter != rt_mutex_top_waiter(lock)) return 0; } @@ -369,7 +462,7 @@ static int try_to_take_rt_mutex(struct r /* remove the queued waiter. */ if (waiter) { - plist_del(&waiter->list_entry, &lock->wait_list); + rt_mutex_dequeue(lock, waiter); task->pi_blocked_on = NULL; } @@ -379,8 +472,7 @@ static int try_to_take_rt_mutex(struct r */ if (rt_mutex_has_waiters(lock)) { top = rt_mutex_top_waiter(lock); - top->pi_list_entry.prio = top->list_entry.prio; - plist_add(&top->pi_list_entry, &task->pi_waiters); + rt_mutex_enqueue_pi(task, top); } raw_spin_unlock_irqrestore(&task->pi_lock, flags); } @@ -416,13 +508,11 @@ static int task_blocks_on_rt_mutex(struc __rt_mutex_adjust_prio(task); waiter->task = task; waiter->lock = lock; - plist_node_init(&waiter->list_entry, task->prio); - plist_node_init(&waiter->pi_list_entry, task->prio); /* Get the top priority waiter on the lock */ if (rt_mutex_has_waiters(lock)) top_waiter = rt_mutex_top_waiter(lock); - plist_add(&waiter->list_entry, &lock->wait_list); + rt_mutex_enqueue(lock, waiter); task->pi_blocked_on = waiter; @@ -433,8 +523,8 @@ static int task_blocks_on_rt_mutex(struc if (waiter == rt_mutex_top_waiter(lock)) { raw_spin_lock_irqsave(&owner->pi_lock, flags); - plist_del(&top_waiter->pi_list_entry, &owner->pi_waiters); - plist_add(&waiter->pi_list_entry, &owner->pi_waiters); + rt_mutex_dequeue_pi(owner, top_waiter); + rt_mutex_enqueue_pi(owner, waiter); __rt_mutex_adjust_prio(owner); if (owner->pi_blocked_on) @@ -486,7 +576,7 @@ static void wakeup_next_waiter(struct rt * boosted mode and go back to normal after releasing * lock->wait_lock. */ - plist_del(&waiter->pi_list_entry, ¤t->pi_waiters); + rt_mutex_dequeue_pi(current, waiter); rt_mutex_set_owner(lock, NULL); @@ -510,7 +600,7 @@ static void remove_waiter(struct rt_mute int chain_walk = 0; raw_spin_lock_irqsave(¤t->pi_lock, flags); - plist_del(&waiter->list_entry, &lock->wait_list); + rt_mutex_dequeue(lock, waiter); current->pi_blocked_on = NULL; raw_spin_unlock_irqrestore(¤t->pi_lock, flags); @@ -521,13 +611,13 @@ static void remove_waiter(struct rt_mute raw_spin_lock_irqsave(&owner->pi_lock, flags); - plist_del(&waiter->pi_list_entry, &owner->pi_waiters); + rt_mutex_dequeue_pi(owner, waiter); if (rt_mutex_has_waiters(lock)) { struct rt_mutex_waiter *next; next = rt_mutex_top_waiter(lock); - plist_add(&next->pi_list_entry, &owner->pi_waiters); + rt_mutex_enqueue_pi(owner, next); } __rt_mutex_adjust_prio(owner); @@ -537,8 +627,6 @@ static void remove_waiter(struct rt_mute raw_spin_unlock_irqrestore(&owner->pi_lock, flags); } - WARN_ON(!plist_node_empty(&waiter->pi_list_entry)); - if (!chain_walk) return; @@ -565,7 +653,7 @@ void rt_mutex_adjust_pi(struct task_stru raw_spin_lock_irqsave(&task->pi_lock, flags); waiter = task->pi_blocked_on; - if (!waiter || waiter->list_entry.prio == task->prio) { + if (!waiter || waiter->task->prio == task->prio) { raw_spin_unlock_irqrestore(&task->pi_lock, flags); return; } @@ -638,6 +726,8 @@ rt_mutex_slowlock(struct rt_mutex *lock, int ret = 0; debug_rt_mutex_init_waiter(&waiter); + RB_CLEAR_NODE(&waiter.pi_tree_entry); + RB_CLEAR_NODE(&waiter.tree_entry); raw_spin_lock(&lock->wait_lock); @@ -904,7 +994,8 @@ void __rt_mutex_init(struct rt_mutex *lo { lock->owner = NULL; raw_spin_lock_init(&lock->wait_lock); - plist_head_init(&lock->wait_list); + lock->waiters = RB_ROOT; + lock->waiters_leftmost = NULL; debug_rt_mutex_init(lock, name); } --- a/kernel/locking/rtmutex_common.h +++ b/kernel/locking/rtmutex_common.h @@ -40,13 +40,13 @@ extern void schedule_rt_mutex_test(struc * This is the control structure for tasks blocked on a rt_mutex, * which is allocated on the kernel stack on of the blocked task. * - * @list_entry: pi node to enqueue into the mutex waiters list - * @pi_list_entry: pi node to enqueue into the mutex owner waiters list + * @tree_entry: pi node to enqueue into the mutex waiters tree + * @pi_tree_entry: pi node to enqueue into the mutex owner waiters tree * @task: task reference to the blocked task */ struct rt_mutex_waiter { - struct plist_node list_entry; - struct plist_node pi_list_entry; + struct rb_node tree_entry; + struct rb_node pi_tree_entry; struct task_struct *task; struct rt_mutex *lock; #ifdef CONFIG_DEBUG_RT_MUTEXES @@ -57,11 +57,11 @@ struct rt_mutex_waiter { }; /* - * Various helpers to access the waiters-plist: + * Various helpers to access the waiters-tree: */ static inline int rt_mutex_has_waiters(struct rt_mutex *lock) { - return !plist_head_empty(&lock->wait_list); + return !RB_EMPTY_ROOT(&lock->waiters); } static inline struct rt_mutex_waiter * @@ -69,8 +69,8 @@ rt_mutex_top_waiter(struct rt_mutex *loc { struct rt_mutex_waiter *w; - w = plist_first_entry(&lock->wait_list, struct rt_mutex_waiter, - list_entry); + w = rb_entry(lock->waiters_leftmost, struct rt_mutex_waiter, + tree_entry); BUG_ON(w->lock != lock); return w; @@ -78,14 +78,14 @@ rt_mutex_top_waiter(struct rt_mutex *loc static inline int task_has_pi_waiters(struct task_struct *p) { - return !plist_head_empty(&p->pi_waiters); + return !RB_EMPTY_ROOT(&p->pi_waiters); } static inline struct rt_mutex_waiter * task_top_pi_waiter(struct task_struct *p) { - return plist_first_entry(&p->pi_waiters, struct rt_mutex_waiter, - pi_list_entry); + return rb_entry(p->pi_waiters_leftmost, struct rt_mutex_waiter, + pi_tree_entry); } /* --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6625,10 +6625,6 @@ void __init sched_init(void) INIT_HLIST_HEAD(&init_task.preempt_notifiers); #endif -#ifdef CONFIG_RT_MUTEXES - plist_head_init(&init_task.pi_waiters); -#endif - /* * The boot idle thread does lazy MMU switching as well: */