Messages in this thread | | | Subject | Re: Performance regression from switching lock to rw-sem for anon-vma tree | From | Tim Chen <> | Date | Mon, 17 Jun 2013 15:27:46 -0700 |
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On Fri, 2013-06-14 at 15:47 -0700, Michel Lespinasse wrote: > On Fri, Jun 14, 2013 at 3:31 PM, Davidlohr Bueso <davidlohr.bueso@hp.com> wrote: > > A few ideas that come to mind are avoiding taking the ->wait_lock and > > avoid dealing with waiters when doing the optimistic spinning (just like > > mutexes do). > > > > I agree that we should first deal with the optimistic spinning before > > adding the MCS complexity. > > Maybe it would be worth disabling the MCS patch in mutex and comparing > that to the rwsem patches ? Just to make sure the rwsem performance > delta isn't related to that. >
I've tried to back out the MCS patch. In fact, for exim, it is about 1% faster without MCS. So the better performance of mutex I saw was not due to MCS. Thanks for the suggestion.
Tim
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