On Wed, 2014-06-04 at 12:08 -0700, Jason Low wrote: > In __mutex_trylock_slowpath(), we acquire the wait_lock spinlock, > xchg() lock->count with -1, then set lock->count back to 0 if there > are no waiters, and return true if the prev lock count was 1. > > However, if we the mutex is already locked, then there may not be ^^ leave that out.
> much point in attempting the above operations. Isn't this redundant? I mean, if we enter the slowpath its because __mutex_fastpath_trylock() already failed so we already know that the lock is taken. What kind of testing has this change been put through? Any advantages? (ie: how many cycles are we saving here?), the trylock mechanism is already pretty darn fast. Thanks, Davidlohr -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/