Re: [RFC/PATCH] FUSYN Realtime & robust mutexes for Linux, v2.3.1

[Linh Dang <linhd@nortelnetworks.com>]

Ulrich Drepper <drepper@redhat.com> wrote:
> The fast path for all locking primitives etc in nptl today is
> entirely at userlevel.  Normally just a single atomic operation with
> a dozen other instructions.  With the fusyn stuff each and every
> locking operation needs a system call to register/unregister the
> thread as it locks/unlocks mutex/rwlocks/etc.  Go figure how well
> this works.  We are talking about making the fast path of the
> locking primitives two/three/four orders of magnitude more
> expensive.  And this for absolutely no benefit for 99.999% of all
> the code which uses threads.
>

Is there an EFFICIENT way to add priority-inheritance to futex? the
lack of priority-inheritance is biggest headache for RT applications
running on top of NPTL/kernel-2.6. And there's is a LOT more of us (RT
users who want to use NPTL/kernel-2.6) than you might think. I guess
we're just not vocal.

-- 
Linh Dang