This message generated a parse failure. Raw output follows here. Please use 'back' to navigate. From devnull@lkml.org Thu Apr 25 07:58:05 2024 Received: from entropy.muc.muohio.edu (entropy.muc.muohio.edu [134.53.213.10]) by herbie.ucs.indiana.edu (8.8.8/8.8.8) with ESMTP id IAA12816 for ; Fri, 26 Feb 1999 08:57:38 -0500 (EST) Received: from vger.rutgers.edu (vger.rutgers.edu [128.6.190.2]) by entropy.muc.muohio.edu (Postfix) with ESMTP id E814122340; Fri, 26 Feb 1999 08:38:05 -0500 (EST) Received: by vger.rutgers.edu via listexpand id <157035-25208>; Fri, 26 Feb 1999 07:28:23 -0500 Received: by vger.rutgers.edu id <156929-25206>; Fri, 26 Feb 1999 07:28:02 -0500 Received: from gateway.ukaea.org.uk ([194.128.63.74]:2870 "EHLO ukaea.org.uk" ident: "SOCKWRITE-65") by vger.rutgers.edu with ESMTP id <156926-25208>; Fri, 26 Feb 1999 07:27:46 -0500 Received: by gateway.ukaea.org.uk id <66317>; Fri, 26 Feb 1999 13:33:14 +0000 Message-Id: <99Feb26.133314gmt.66317@gateway.ukaea.org.uk> Date: Fri, 26 Feb 1999 13:38:14 +0000 From: Neil Conway Organization: Fusion X-Mailer: Mozilla 4.06 [en] (X11; I; Linux 2.0.35 i686) Mime-Version: 1.0 To: root@chaos.analogic.com, "linux-kernel@vger.rutgers.edu" Subject: Re: [offtopic] Re: 2.2.2: 2 thumbs up from lm References: Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-linux-kernel@vger.rutgers.edu Precedence: bulk X-Loop: majordomo@vger.rutgers.edu X-Orcpt: rfc822;linux-kernel-outgoing-dig [This one will defo be my last list posting on this matter (honest!).] Richard B. Johnson wrote: > On Fri, 26 Feb 1999, Neil Conway wrote: > [SNIPPED] > > > > But how can you promise the customer that your system will respond to > > events while they are current if you DON'T control the latency? > > > > This is the crux. > > I have a CPU which does nothing but poll a port. I want to detect > when the sun comes up which happens once a day. There is a photo > controller relay connected to that port. I need to know this time > within one second. > > Therefore I need to poll this port at least twice per second. > Twice comes from Shannon since this has become a sampled system. (Well that's not an appropriate application of sampling theory. If you only need to know to within 1 second, then you only have to sample at <1 second intervals. So 0.9 second intervals would be just fine. But that's fluff.) > Do we care how much time it takes to poll this port as long as > the specified conditions are met? This is the latency and, in > fact we don't care as long as the required specifications are > met. If the latency is 1/2 second, we can't guarantee that the > port is polled twice per second. However, if the latency is > one microfortnight less than 1/2 second we can. Well, substitute (<1second) for every (1/2second) and I totally agree with you. No argument whatever. In my thinking, you must simply bound the latency of your system to this upper limit. End of story. I never said anything to contradict what you just said, in fact I thought that's exactly what _I_ said :-). I don't think we have any disagreement here so we must just have misunderstood each other - if I'm at fault then I wholeheartedly apologise for any confusion... Neil - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/