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Is MTX_CONTESTED evil?



On Mon, 22 Mar 2004, 19:06-0500, John Baldwin wrote:

[...]
> > By the way, one thing to keep in mind is that Solaris has working
> > adaptive mutexes.  For adaptive mutexes, the waiting case is
> > almost never supposed to happen, so it's more reasonable for them
> > to wake all waiters.  However, AFAIK, FreeBSD's adaptive mutex
> > support is incomplete or broken at this point, so you may run into
> > a thundering herd problem if you wake all waiters.
>
> Adaptive mutexes work just fine, but they aren't on by default.  In FreeBSD,
> adaptive mutexes spin so long as the owner is still executing on another CPU.

With 'options ADATIVE_MUTEXES' our SMP testbox crashes very reliable.
If you are interested in a traceback and/or crashdump let me know.

-- 
Maxim Konovalov