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lockmgr: save on sleepq when cmpset fails

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This commit is contained in:
mjg 2018-03-05 00:30:07 +00:00
parent b2d136be8c
commit fb232db34a
1 changed files with 20 additions and 14 deletions
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34
sys/kern/kern_lock.c
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@ -296,7 +296,7 @@ sleeplk(struct lock *lk, u_int flags, struct lock_object *ilk,
static __inline int
wakeupshlk(struct lock *lk, const char *file, int line)
{
uintptr_t v, x;
uintptr_t v, x, orig_x;
u_int realexslp;
int queue, wakeup_swapper;
@ -311,7 +311,9 @@ wakeupshlk(struct lock *lk, const char *file, int line)
* path in order to handle wakeups correctly.
*/
sleepq_lock(&lk->lock_object);
x = lk->lk_lock & (LK_ALL_WAITERS | LK_EXCLUSIVE_SPINNERS);
orig_x = lk->lk_lock;
retry_sleepq:
x = orig_x & (LK_ALL_WAITERS | LK_EXCLUSIVE_SPINNERS);
v = LK_UNLOCKED;
/*
@ -360,10 +362,15 @@ wakeupshlk(struct lock *lk, const char *file, int line)
queue = SQ_SHARED_QUEUE;
}
if (!atomic_cmpset_rel_ptr(&lk->lk_lock, LK_SHARERS_LOCK(1) | x,
v)) {
if (lockmgr_sunlock_try(lk, &orig_x)) {
sleepq_release(&lk->lock_object);
continue;
break;
}
x |= LK_SHARERS_LOCK(1);
if (!atomic_fcmpset_rel_ptr(&lk->lk_lock, &x, v)) {
orig_x = x;
goto retry_sleepq;
}
LOCK_LOG3(lk, "%s: %p waking up threads on the %s queue",
__func__, lk, queue == SQ_SHARED_QUEUE ? "shared" :
@ -602,6 +609,7 @@ lockmgr_slock_hard(struct lock *lk, u_int flags, struct lock_object *ilk,
*/
sleepq_lock(&lk->lock_object);
x = lk->lk_lock;
retry_sleepq:
/*
* if the lock can be acquired in shared mode, try
@ -617,10 +625,9 @@ lockmgr_slock_hard(struct lock *lk, u_int flags, struct lock_object *ilk,
* loop back and retry.
*/
if ((x & LK_SHARED_WAITERS) == 0) {
if (!atomic_cmpset_acq_ptr(&lk->lk_lock, x,
if (!atomic_fcmpset_acq_ptr(&lk->lk_lock, &x,
x | LK_SHARED_WAITERS)) {
sleepq_release(&lk->lock_object);
continue;
goto retry_sleepq;
}
LOCK_LOG2(lk, "%s: %p set shared waiters flag",
__func__, lk);
@ -755,6 +762,7 @@ lockmgr_xlock_hard(struct lock *lk, u_int flags, struct lock_object *ilk,
*/
sleepq_lock(&lk->lock_object);
x = lk->lk_lock;
retry_sleepq:
/*
* if the lock has been released while we spun on
@ -777,7 +785,7 @@ lockmgr_xlock_hard(struct lock *lk, u_int flags, struct lock_object *ilk,
v = x & (LK_ALL_WAITERS | LK_EXCLUSIVE_SPINNERS);
if ((x & ~v) == LK_UNLOCKED) {
v &= ~LK_EXCLUSIVE_SPINNERS;
if (atomic_cmpset_acq_ptr(&lk->lk_lock, x,
if (atomic_fcmpset_acq_ptr(&lk->lk_lock, &x,
tid | v)) {
sleepq_release(&lk->lock_object);
LOCK_LOG2(lk,
@ -785,8 +793,7 @@ lockmgr_xlock_hard(struct lock *lk, u_int flags, struct lock_object *ilk,
__func__, lk);
break;
}
sleepq_release(&lk->lock_object);
continue;
goto retry_sleepq;
}
/*
@ -794,10 +801,9 @@ lockmgr_xlock_hard(struct lock *lk, u_int flags, struct lock_object *ilk,
* fail, loop back and retry.
*/
if ((x & LK_EXCLUSIVE_WAITERS) == 0) {
if (!atomic_cmpset_ptr(&lk->lk_lock, x,
if (!atomic_fcmpset_ptr(&lk->lk_lock, &x,
x | LK_EXCLUSIVE_WAITERS)) {
sleepq_release(&lk->lock_object);
continue;
goto retry_sleepq;
}
LOCK_LOG2(lk, "%s: %p set excl waiters flag",
__func__, lk);