On Mon, Aug 03, 2015 at 04:05:33PM -0400, Steven Rostedt wrote: > On Thu, 30 Jul 2015 17:40:01 +0200 > Peter Zijlstra <pet...@infradead.org> wrote: > > > On Thu, Jul 30, 2015 at 08:34:52AM -0700, Paul E. McKenney wrote: > > > > If the extra read before the cmpxchg() does not hurt, we should do the > > > > same for mutex and make the above redundant. > > > > > > I am pretty sure that different hardware wants it done differently. :-/ > > > So I agree that hard data would be good. > > > > > > I could probably further optimize the RCU code by checking for a > > > single-node tree, but I am not convinced that this is worthwhile. > > > However, skipping three cache misses in the uncontended case is > > > definitely worthwhile, hence this patch. ;-) > > > > I was mostly talking about the !mutex_is_locked() && mutex_try_lock() > > thing. The fast path thing makes sense. > > Note, mutex does do this for the optimistic spin. See > mutex_try_to_aquire().
Right but that's mutex_lock(). mutex_trylock() does not. -- 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/
