Messages in this thread Patch in this message | | | From | Gregory Haskins <> | Subject | [PATCH 4/5] adjust pi_lock usage in wakeup | Date | Tue, 20 May 2008 10:49:31 -0400 |
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From: Peter W.Morreale <pmorreale@novell.com>
In wakeup_next_waiter(), we take the pi_lock, and then find out whether we have another waiter to add to the pending owner. We can reduce contention on the pi_lock for the pending owner if we first obtain the pointer to the next waiter outside of the pi_lock.
Signed-off-by: Peter W. Morreale <pmorreale@novell.com> Signed-off-by: Gregory Haskins <ghaskins@novell.com> ---
kernel/rtmutex.c | 14 +++++++++----- 1 files changed, 9 insertions(+), 5 deletions(-)
diff --git a/kernel/rtmutex.c b/kernel/rtmutex.c index b6ff1eb..ec1f7d4 100644 --- a/kernel/rtmutex.c +++ b/kernel/rtmutex.c @@ -506,6 +506,7 @@ static void wakeup_next_waiter(struct rt_mutex *lock, int savestate) { struct rt_mutex_waiter *waiter; struct task_struct *pendowner; + struct rt_mutex_waiter *next; spin_lock(¤t->pi_lock); @@ -568,6 +569,12 @@ static void wakeup_next_waiter(struct rt_mutex *lock, int savestate) * waiter with higher priority than pending-owner->normal_prio * is blocked on the unboosted (pending) owner. */ + + if (rt_mutex_has_waiters(lock)) + next = rt_mutex_top_waiter(lock); + else + next = NULL; + spin_lock(&pendowner->pi_lock); WARN_ON(!pendowner->pi_blocked_on); @@ -576,12 +583,9 @@ static void wakeup_next_waiter(struct rt_mutex *lock, int savestate) pendowner->pi_blocked_on = NULL; - if (rt_mutex_has_waiters(lock)) { - struct rt_mutex_waiter *next; - - next = rt_mutex_top_waiter(lock); + if (next) plist_add(&next->pi_list_entry, &pendowner->pi_waiters); - } + spin_unlock(&pendowner->pi_lock); }
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