From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pradyumna Sampath Subject: Re: preempt rt in commercial use Date: Tue, 14 Sep 2010 16:44:43 +0200 Message-ID: References: <201009141317.13439@zigzag.lvk.cs.msu.su> <20100914094411.GB10841@pengutronix.de> <4C8F8500.5070002@theptrgroup.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Robert Schwebel , Raz , "Nikita V. Youshchenko" , linux-rt-users To: Jeff Angielski Return-path: Received: from mail-bw0-f46.google.com ([209.85.214.46]:49183 "EHLO mail-bw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754298Ab0INOoo convert rfc822-to-8bit (ORCPT ); Tue, 14 Sep 2010 10:44:44 -0400 Received: by bwz11 with SMTP id 11so5551973bwz.19 for ; Tue, 14 Sep 2010 07:44:43 -0700 (PDT) In-Reply-To: <4C8F8500.5070002@theptrgroup.com> Sender: linux-rt-users-owner@vger.kernel.org List-ID: Hi, On Tue, Sep 14, 2010 at 4:21 PM, Jeff Angielski = wrote: > No. =A0Preempt rt it's not hard realtime. > > But most people/companies who think they need hard realtime really do= n't. > =A0They can live with soft realtime and have a really low probability= of > missing deadlines and having long latencies. =A0For these people, the= preempt > rt is adequate. I agree. Hard, soft ... far too qualitative for a discussion like this. Numbers, test cases and applications determine different meanings of these words. Top copy a phrase from one of the presentations from dresden. Real-time need not always be real fast. hard Real-time =3D Speed + Determinism So hard real time is a moving target. Would I use RT_PREEMPT to run servo loops at 60 microseconds on a 160 Mhz powerpc ? Surely not ! Or not yet. my 2 cents. regards /prady --=20 http://www.prady.in -- To unsubscribe from this list: send the line "unsubscribe linux-rt-user= s" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html