From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=ham autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,dfedbe83126d2210 X-Google-Attributes: gid103376,public X-Google-ArrivalTime: 2001-11-27 07:42:12 PST Path: archiver1.google.com!news1.google.com!newsfeed.stanford.edu!newsfeeds.belnet.be!news.belnet.be!uni-erlangen.de!news-nue1.dfn.de!newsfeed.r-kom.de!newsfeed.stueberl.de!newsfeed.vmunix.org!newsfeed2.easynews.net!easynews.net!news.cid.net!news.enyo.de!news1.enyo.de!not-for-mail From: Florian Weimer Newsgroups: comp.lang.ada Subject: Re: Anyone using Ada with Real-Time Linux? Date: Tue, 27 Nov 2001 17:06:01 +0100 Organization: Enyo's not your organization Message-ID: <877ksc2o7q.fsf@deneb.enyo.de> References: <8QcM7.77531$XJ4.41637211@news1.sttln1.wa.home.com> <3c034fbb.1313812@News.CIS.DFN.DE> <3c039d8c.21235968@News.CIS.DFN.DE> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cancel-Lock: sha1:FqE+/ze0WPNcg7ADiwvAv19CQRk= Xref: archiver1.google.com comp.lang.ada:17047 Date: 2001-11-27T17:06:01+01:00 List-Id: dmitry@elros.cbb-automation.de (Dmitry A. Kazakov) writes: > [We are considering which OS platform to choose for an embedded "soft" > real-time system. Our requirements are: 5 ms for the DAQ & control > task and almost "no matter" for the TCP/IP tasks] If the 5ms are a *requirement*, it's not "soft" real time. ;-) (And you shouldn't use a standard Linux version.) >>Whether this would fit the requirement I don't know; there might be >>unavoidable delays, as Dmitry says. > > I heard that the Linux kernel is (or will be) preemptive. If so, there > [I suppose] should be no big problem with I/O? Usually, I/O isn't the problem. Some FS operations and console switching are major offenders, IIRC. Perhaps you don't need a preemptive kernel. For 2.2.x, there are patches which add additional scheduling points to lower average latency (but I don't know if you get an exact 5ms timing, perhaps with a kernel module using the real-time clock interrupt).