Is MTX_CONTESTED evil?

[John Baldwin]

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 Smørgrav) 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.

-- 
John Baldwin <jhb at FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve"  =  http://www.FreeBSD.org