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,FREEMAIL_FROM autolearn=unavailable autolearn_force=no version=3.4.4 X-Received: by 10.236.108.228 with SMTP id q64mr5167380yhg.36.1391774966726; Fri, 07 Feb 2014 04:09:26 -0800 (PST) X-Received: by 10.140.95.144 with SMTP id i16mr298411qge.1.1391774966665; Fri, 07 Feb 2014 04:09:26 -0800 (PST) Path: eternal-september.org!reader01.eternal-september.org!reader02.eternal-september.org!news.eternal-september.org!news.eternal-september.org!news.eternal-september.org!feeder.eternal-september.org!news.bbs-scene.org!border4.nntp.dca.giganews.com!border2.nntp.dca.giganews.com!nntp.giganews.com!f11no13396917qae.1!news-out.google.com!s3ni9959qas.0!nntp.google.com!f11no13396500qae.1!postnews.google.com!glegroupsg2000goo.googlegroups.com!not-for-mail Newsgroups: comp.lang.ada Date: Fri, 7 Feb 2014 04:09:26 -0800 (PST) In-Reply-To: <85d2iz1g48.fsf@stephe-leake.org> Complaints-To: groups-abuse@google.com Injection-Info: glegroupsg2000goo.googlegroups.com; posting-host=189.77.226.1; posting-account=TRgI1QoAAABSsYi-ox3Pi6N-JEKKU0cu NNTP-Posting-Host: 189.77.226.1 References: <5e8fad3a-94e6-4517-af54-db8b4146803e@googlegroups.com> <858uto3cj3.fsf@stephe-leake.org> <85d2iz1g48.fsf@stephe-leake.org> User-Agent: G2/1.0 MIME-Version: 1.0 Message-ID: Subject: Re: Raspberry Pi, Real-Time and Ada From: "Rego, P." Injection-Date: Fri, 07 Feb 2014 12:09:26 +0000 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Xref: news.eternal-september.org comp.lang.ada:18422 Date: 2014-02-07T04:09:26-08:00 List-Id: On Friday, February 7, 2014 6:28:23 AM UTC-2, Stephen Leake wrote: > Ok, good. > What is your application? In short, drones.=20 > What are your timing requirements? For the next application I think I will need achieve 1 ms for I/O access in= hard RT, and up to 100 us for pure computation for soft RT. > I think you are asking: > "How do you know the RPi can meet 0.1 second tolerances?" > I've seen one running Emacs, and it responds well to keyboard commands. > Humans notice delays longer than 0.1 seconds, so that's my metric. Ok, it makes sense. In this case, I also get to run GPS on it, and I cannot= feel any delay to the keyboard. > Why do you think 0.1 seconds is "slow"? > If the application is flying a spacecraft to Jupiter, then 1 day is > "fast" during the coast phase, when nothing much is happening. > "fast" and "slow" are totally determined by the application. Indeed. Yes, I will need much faster. > That's heavily application dependent. > If your application is some sort of control system, then it reads > inputs, computes, and writes outputs. > Using an oscilloscope, measure the time from an input signal to a > related output signal. I was thinking more on some sw tools made for measuring hw performance. A t= ime ago I used some tools for evaluating performance of parallel machines w= ith MPI and OpenMP (I don't remember the names now), thought it could have = some of these in RPi. Anyway measuring the outputs would be a very good sta= rting point. -- Rego.