Date: Fri, 05 Jun 1998 18:28:40 -0700 From: Mike Smith <mike@smith.net.au> To: "Caleb R. Miller" <calebm@uspaceware.com> Cc: "'hackers@freebsd.org'" <hackers@FreeBSD.ORG> Subject: Re: FreeBSD as a RTOS Message-ID: <199806060128.SAA02622@dingo.cdrom.com> In-Reply-To: Your message of "Fri, 05 Jun 1998 13:45:08 MDT." <01BD9088.27E19890@CALEBM>
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Please expend a little effort formatting your messages; you are likely to find people much more disposed to responding to them if you do this. > Does anyone know of a FreeBSD port that supports RTOS functionality > such as preemptive multitasking? FreeBSD already supports preemtive multitasking. > What I hoping for was a scheduler that > would enforce time constraints on processes. The current scheduler already enforces time constraints on processes. > For instance, I want to > schedule some processes to be allowed to run 4 times/sec, some 2 times/ > sec and some once/sec. If this is the sort of granularity you require, you can achieve this with the current (10ms) scheduler granularity already. > The scheduler would let give the highest rate > process time, then the next higher rate, and so on with the caveat that > a process gets no more cpu time than it's scheduled for, i.e. if process > A is scheduled for every 30 seconds and process B for every 15 seconds, > if A is not done by the next 15 second interval it is preempted and B is > allowed to run. Whilst there are various realtime extensions to FreeBSD available and under development, I don't think that any of them offer anything that you require. If you require more information on the topic before going further, you may want to collect a book on the various Posix realtime scheduling extensions, which are available for FreeBSD on an evaluation basis, and which will be part of the 3.0 release Q4 this year. -- \\ Sometimes you're ahead, \\ Mike Smith \\ sometimes you're behind. \\ mike@smith.net.au \\ The race is long, and in the \\ msmith@freebsd.org \\ end it's only with yourself. \\ msmith@cdrom.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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