Is MTX_CONTESTED evil?

[Kris Kennaway]

On Fri, Mar 26, 2004 at 02:04:57PM -0500, John Baldwin wrote:
> On Friday 26 March 2004 01:37 pm, M. Warner Losh wrote:
> > In message: <xzpekrgf103.fsf at dwp.des.no>
> >
> >             des at des.no (Dag-Erling Sm?rgrav) writes:
> > : "Brian F. Feldman" <green at FreeBSD.org> writes:
> > : > Well, that certainly explains the blitz of crashes I had to fix
> > : > recently!  Since INVARIANTS and WITNESS are on by default, it would
> > : > make sense to make ADAPTIVE_MUTEX default to catch more bugs.
> > :
> > : Making ADAPTIVE_MUTEXES default will not catch more bugs, it will just
> > : piss off users.
> >
> > I think that if we don't fix the class of bugs that AM points out,
> > we'll ruin our reputation as a quality system in the long run.  Maybe
> > they are so pervasive that we don't want to turn it on by default just
> > yet, but there will come a time we turn it on, just like we turned on
> > WITNESS and INVARIANTS to get better coverage on our testing.
> 
> Right, let's not just gratuitously break everyone right yet.  It's actually an 
> option largely b/c I want us to be able to benchmark it once our locking is 
> farther along to see if it helps more than it hurts.

FYI, I'm going to run with this on the bento cluster for a bit to dig
out some of these bugs.

Kris
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