TSX lock elision for glibc v10

[Dominik Vogt]

On Thu, Jun 13, 2013 at 11:07:53PM +0200, Andi Kleen wrote:
> > > Only requiring opt-in would kill a lot of the benefits from 
> > > putting this into glibc.  Disabling any nesting would also kill a lot of the
> > > benefit.
> > 
> > Adding a separate constant for NORMAL type mutexes would fix the issue
> > completely and could be done right now without any controversy.
> 
> But old executables don't know anything about new constants.
> They just use "0".  Such a change would only affect rebuilt programs.
> 
> The important part for me is also that default is able to elide.

I don't think a feature that has the potential to cut performance
in half in certain corner cases should be enabled by default
without thorough field testing.

Ciao

Dominik ^_^  ^_^

-- 

Dominik Vogt
IBM Germany