From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nicholas Mc Guire Subject: Re: I/O operations priority in RTOS Date: Sun, 5 Jun 2011 11:28:54 +0200 Message-ID: <20110605092854.GA7576@opentech.at> References: <4DEA1BA9.7020303@unican.es> <4DEA1F22.6000603@unican.es> <20110604234214.GA30640@opentech.at> <4DEB427F.9020104@steinhoff.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Monica Puig-Pey , linux-rt-users@vger.kernel.org To: Armin Steinhoff Return-path: Received: from hofr.at ([212.69.189.236]:46289 "EHLO mail.hofr.at" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755465Ab1FEJ2z (ORCPT ); Sun, 5 Jun 2011 05:28:55 -0400 Content-Disposition: inline In-Reply-To: <4DEB427F.9020104@steinhoff.de> Sender: linux-rt-users-owner@vger.kernel.org List-ID: 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. hofrat