RTCoreBSD
Bsderss
snort_sam at yahoo.com
Wed Aug 10 13:05:30 GMT 2005
--- Robert Watson <rwatson at FreeBSD.org> wrote:
>
> On Wed, 10 Aug 2005, Momtchil Momtchev wrote:
>
> > No, kqueue/kevent is not realtime, as the whole
> FreeBSD kernel doesn't
> > support hard real-time scheduling. In order to
> have hard real-time
> > scheduling you should have a fully preemtible
> kernel, which schedules
> > and preempts everything (even interrupt handlers).
> The RTCoreBSD uses a
> > two-kernel approach with a real-time microkernel
> which runs the FreeBSD
> > kernel as a process, providing a virtual interrupt
> controller. The
> > real-time processes run directly on the
> microkernel and can't directly
> > use the FreeBSD kernel services.
>
> While FreeBSD is not a hard realtime system, it does
> have increasing
> propertis of one: FreeBSD 6.0 ships with kernel
> preemption enabled by
> default, and the priority propagation and priority
> management in the SMPng
> locking primitives moves in that direction also.
> FreeBSD will preempt one
> running ithread with one associated with a new
> interrupt if the scheduler
> decides that's appropriate based on their
> priorities. With Giant off most
> of the kernel, a lot of problems with deferred
> processing due to large
> lock size have gone away.
>
What will be this affect to our multi-threaded and
multiplex programming?
Sam
> Robert N M Watson
> _______________________________________________
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