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authorDavidlohr Bueso <dave@stgolabs.net>2015-05-19 10:24:55 -0700
committerThomas Gleixner <tglx@linutronix.de>2015-06-18 22:27:46 +0200
commit45ab4effc3bee6f8a5cb05652b7bb895ec5b6a7a (patch)
tree330e0f345b3f5e485e0e1ba6926c9d2dd3c5350e /kernel/futex.c
parent6f9aad0bc37286c0441b57f0ba8cffee50715426 (diff)
downloadlinux-45ab4effc3bee6f8a5cb05652b7bb895ec5b6a7a.tar.bz2
locking/rtmutex: Implement lockless top-waiter wakeup
Mark the task for later wakeup after the wait_lock has been released. This way, once the next task is awoken, it will have a better chance to of finding the wait_lock free when continuing executing in __rt_mutex_slowlock() when trying to acquire the rtmutex, calling try_to_take_rt_mutex(). Upon contended scenarios, other tasks attempting take the lock may acquire it first, right after the wait_lock is released, but (a) this can also occur with the current code, as it relies on the spinlock fairness, and (b) we are dealing with the top-waiter anyway, so it will always take the lock next. Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Mike Galbraith <umgwanakikbuti@gmail.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1432056298-18738-2-git-send-email-dave@stgolabs.net Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel/futex.c')
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