On Sun, Nov 2, 2014 at 8:10 PM, Konstantin Belousov <kostik...@gmail.com> wrote: > On Sun, Nov 02, 2014 at 06:53:44PM +0100, Attilio Rao wrote: >> > I did not proposed to verify owner chain. I said that it is easy to >> > record the locks owned by current thread, only for current thread >> > consumption. Below is the prototype. >> >> I think it is too expensive, think that this must happen for every shared >> lock. >> I know we may not be using too many shared locks on lockmgr right now, >> but it is not a good reason to make shared lock bloated and more >> expensive on lockmgr. > > It can be significantly simplified, if the array of lock pointers is > kept dense. Then the only non-trivial operation is unlock out of order, > when the array have to be compacted. > > The code adds one write and n reads on shared lock, where n is the > number of shared-locked locks already owned by thread. Typical n is 0 > or 1. On unlock, if done in order, the code adds one read; unordered > unlock shuffles array elements. Again, for typical lock nesting of 2, > this means one read and one write, and even this is rare. All reads and > writes are for thread-local memory. > > I am not going to spend any more time on this if people do not consider > the lock tracking worth it. Otherwise, I will benchmark the patch.
I think that your initial patch (what is in head now) is a better approach. I would just make it a lockinit() flag to make it less alien to the KPI. Attilio -- Peace can only be achieved by understanding - A. Einstein _______________________________________________ svn-src-all@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
