From mboxrd@z Thu Jan 1 00:00:00 1970 From: Armin Steinhoff Subject: Re: I/O operations priority in RTOS Date: Mon, 06 Jun 2011 00:32:53 +0200 Message-ID: <4DEC0415.8080304@steinhoff.de> References: <4DEA1BA9.7020303@unican.es> <4DEA1F22.6000603@unican.es> <20110604234214.GA30640@opentech.at> <4DEB427F.9020104@steinhoff.de> <20110605092854.GA7576@opentech.at> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Monica Puig-Pey , linux-rt-users@vger.kernel.org To: Nicholas Mc Guire Return-path: Received: from moutng.kundenserver.de ([212.227.17.9]:57782 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756192Ab1FEWXY (ORCPT ); Sun, 5 Jun 2011 18:23:24 -0400 In-Reply-To: <20110605092854.GA7576@opentech.at> Sender: linux-rt-users-owner@vger.kernel.org List-ID: Nicholas Mc Guire wrote: > On Sun, 05 Jun 2011, Armin Steinhoff wrote: > >> Nicholas Mc Guire wrote: >>> On Sat, 04 Jun 2011, Monica Puig-Pey wrote: >>> >>>> Hello, >>>> I'm studying how to develop drivers in a real time OS and how do they >>>> work. I'm using Ubuntu 10.04 with the 2.6.31-11-rt patch installed. >>>> I would like to know the priority when executing open(), read(), write() >>>> and close() operations. >>>> In my example the thread which is using the driver runs with 10 RTPRIO, >>>> but I don't know what happens in kernel context with the priority when >>>> running the I/O operations. >>>> Thank you for your help, I don't know where to learn about this. >>>> >>> [] >>> Also when using bottom half mechanisms you need to take into account the >>> priority of the kernel thread that manages the defered work items, so >>> rt-drivers may have a different structure than normal drivers. >> That's the reason why I prefer UIO based user space drivers ! >> > ...and how to resolve DMA ? if DMA were resolved cleanly I would agree. https://opensource.qualcomm.com/wiki/UIO-DMA I haven't tested until now ... what do you think about it ? --Armin > hofrat >