Date: Wed, 10 Aug 2005 06:06:37 -0700 (PDT) From: Bsderss <snort_sam@yahoo.com> To: Robert Watson <rwatson@FreeBSD.org>, Momtchil Momtchev <momtchil.momtchev@netasq.com> Cc: freebsd-current@freebsd.org, Bsderss <snort_sam@yahoo.com> Subject: Re: RTCoreBSD Message-ID: <20050810130637.89675.qmail@web54408.mail.yahoo.com> In-Reply-To: <20050810131518.T22763@fledge.watson.org>
next in thread | previous in thread | raw e-mail | index | archive | help
--- Robert Watson <rwatson@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 > _______________________________________________ ____________________________________________________ Start your day with Yahoo! - make it your home page http://www.yahoo.com/r/hs
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20050810130637.89675.qmail>