This patch adds several markers around semaphore primitives. Along with a tracing application this patch can be useful for measuring kernel semaphore usage and contention. Signed-off-by: Mike Mason Signed-off-by: David Wilder Signed-off-by: Mathieu Desnoyers --- lib/semaphore-sleepers.c | 9 +++++++++ 1 files changed, 9 insertions(+), 0 deletions(-) diff --git a/lib/semaphore-sleepers.c b/lib/semaphore-sleepers.c index 1281805..5343a96 100644 --- a/lib/semaphore-sleepers.c +++ b/lib/semaphore-sleepers.c @@ -15,6 +15,7 @@ #include #include #include +#include #include /* @@ -50,6 +51,7 @@ fastcall void __up(struct semaphore *sem) { + trace_mark(sem_up, "%p", sem); wake_up(&sem->wait); } @@ -59,6 +61,7 @@ fastcall void __sched __down(struct semaphore * sem) DECLARE_WAITQUEUE(wait, tsk); unsigned long flags; + trace_mark(sem_down, "%p", sem); tsk->state = TASK_UNINTERRUPTIBLE; spin_lock_irqsave(&sem->wait.lock, flags); add_wait_queue_exclusive_locked(&sem->wait, &wait); @@ -73,12 +76,14 @@ fastcall void __sched __down(struct semaphore * sem) * the wait_queue_head. */ if (!atomic_add_negative(sleepers - 1, &sem->count)) { + trace_mark(sem_down_resume, "%p", sem); sem->sleepers = 0; break; } sem->sleepers = 1; /* us - see -1 above */ spin_unlock_irqrestore(&sem->wait.lock, flags); + trace_mark(sem_down_sched, "%p", sem); schedule(); spin_lock_irqsave(&sem->wait.lock, flags); @@ -97,6 +102,7 @@ fastcall int __sched __down_interruptible(struct semaphore * sem) DECLARE_WAITQUEUE(wait, tsk); unsigned long flags; + trace_mark(sem_down_intr, "%p", sem); tsk->state = TASK_INTERRUPTIBLE; spin_lock_irqsave(&sem->wait.lock, flags); add_wait_queue_exclusive_locked(&sem->wait, &wait); @@ -113,6 +119,7 @@ fastcall int __sched __down_interruptible(struct semaphore * sem) * and exit. */ if (signal_pending(current)) { + trace_mark(sem_down_intr_fail, "%p", sem); retval = -EINTR; sem->sleepers = 0; atomic_add(sleepers, &sem->count); @@ -126,12 +133,14 @@ fastcall int __sched __down_interruptible(struct semaphore * sem) * still hoping to get the semaphore. */ if (!atomic_add_negative(sleepers - 1, &sem->count)) { + trace_mark(sem_down_intr_resume, "%p", sem); sem->sleepers = 0; break; } sem->sleepers = 1; /* us - see -1 above */ spin_unlock_irqrestore(&sem->wait.lock, flags); + trace_mark(sem_down_intr_sched, "%p", sem); schedule(); spin_lock_irqsave(&sem->wait.lock, flags); - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ -- Mathieu Desnoyers Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/