Date: Wed, 10 Aug 2005 13:42:14 +0200 From: Momtchil Momtchev <momtchil.momtchev@netasq.com> To: freebsd-current@freebsd.org, Bsderss <snort_sam@yahoo.com> Subject: Re: RTCoreBSD Message-ID: <200508101342.15211.momtchil.momtchev@netasq.com> In-Reply-To: <20050810084015.40585.qmail@web54409.mail.yahoo.com> References: <20050810084015.40585.qmail@web54409.mail.yahoo.com>
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On Wednesday 10 August 2005 10:40, Bsderss wrote: > Hi, > > I found this real-time OS based on BSD: > http://www.sdcsystems.com/realtime-linux.htm#rtcorebsd > > I m wondering what technology they used to make > FreeBSD as a real-time OS. I thought kqueue/kevent is > a key component? any comment? > 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. -- -- Momtchil Momtchev <momtchil.momtchev@netasq.com> R&D Engineer Netasq - Secure Internet Connectivity http://www.netasq.com Tel : +33 320 619 742 Fax : +33 320 619 639
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