Messages in this thread | | | Date | Thu, 5 Aug 2004 00:40:23 -0700 | From | Andrew Morton <> | Subject | Re: [RFC/PATCH] FUSYN Realtime & robust mutexes for Linux, v2.3.1 |
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Ulrich Drepper <drepper@redhat.com> wrote: > > Andrew Morton wrote: > > > How large is the slowdown, and on what workloads? > > 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. >
ouch, OK. But doesn't the current futex code continue to work unchanged?
> > Passing the lock to a non-rt task when there's an rt-task waiting for it > > seems pretty poor form, too. > > No no, that's not what is wanted. Robust mutexes are a special kind of > mutex and not related to rt issues.
I was referring to "scheduling-policy based unlock/wakeup", actually. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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