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=-0.3 required=5.0 tests=BAYES_00, REPLYTO_WITHOUT_TO_CC autolearn=no autolearn_force=no version=3.4.4 Path: border1.nntp.dca1.giganews.com!nntp.giganews.com!goblin3!goblin2!goblin.stu.neva.ru!aioe.org!.POSTED!not-for-mail From: "Dmitry A. Kazakov" Newsgroups: comp.lang.ada Subject: Re: how to analyze clock drift Date: Mon, 24 Nov 2014 19:28:53 +0100 Organization: cbb software GmbH Message-ID: <119jk3v83ilwp$.94ppz78taoc4.dlg@40tude.net> References: <188uppnlnvqgq$.1kjz3jnhjxqji.dlg@40tude.net> <87fvdd38qi.fsf@debian.uxu> <87a93l35dm.fsf@debian.uxu> <9t7t6al8bmifd9krh6koiegttgsvcovadg@4ax.com> <87d28h1cj9.fsf@debian.uxu> <3apu6ap126abi6oalch9vpre20hjij2uon@4ax.com> <87k32oi7r8.fsf@debian.uxu> <98h17atrhtl9kitthjf8ukt1f7rk1ribvc@4ax.com> <8761e54qt2.fsf@debian.uxu> Reply-To: mailbox@dmitry-kazakov.de NNTP-Posting-Host: wfRpp7ltpEWhI2na6kgpfA.user.speranza.aioe.org Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Complaints-To: abuse@aioe.org User-Agent: 40tude_Dialog/2.0.15.1 X-Notice: Filtered by postfilter v. 0.8.2 Xref: number.nntp.giganews.com comp.lang.ada:191004 Date: 2014-11-24T19:28:53+01:00 List-Id: On Mon, 24 Nov 2014 12:24:15 -0500, Dennis Lee Bieber wrote: > On Mon, 24 Nov 2014 09:44:39 +0100, "Dmitry A. Kazakov" > declaimed the following: > >>Setting THREAD_PRIORITY_TIME_CRITICAL blocks practically everything (except >>for drivers). >> >>However I doubt that background processes or services are the problem when >>waiting for 10 or 5ms >> > Many moons ago I had a task using a GFE W98 (!) laptop [needed to be > W9x to allow direct access to the parallel port]. Windows 98 cannot be compared with NT. > Wasn't a timer situation > -- it was more a busy wait since the main timing control was obtained from > an external (1KHz as I recall) clock to a signal pin on the parallel port. > The task required writing 6-bits on each clock transition (I forget if > L->H, or H->L) -- the 6-bits representing three RS-422-style balanced data > lines... You should have written a proper driver for this with interrupts and deferred I/O. BTW, TIME_CRITICAL blocks even deferred I/O processing, if I correctly remember. Windows internals are not that bad as painted. -- Regards, Dmitry A. Kazakov http://www.dmitry-kazakov.de