From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4548A0E8.3070005@domain.hid> Date: Wed, 01 Nov 2006 14:28:08 +0100 From: Wolfgang Grandegger MIME-Version: 1.0 Subject: Re: [Xenomai-help] RTDM/ALSA hybrid driver ? References: <200610251610.36530.witzel.thomas@domain.hid> <200611010018.34412.witzel.thomas@domain.hid> <200611011558.17164.rlenglet@domain.hid> <200611010745.23388.witzel.thomas@domain.hid> In-Reply-To: <200611010745.23388.witzel.thomas@domain.hid> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit List-Id: Help regarding installation and common use of Xenomai List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: witzel.thomas@domain.hid Cc: xenomai@xenomai.org Thomas Witzel wrote: > On Wednesday 01 November 2006 01:58, Romain Lenglet wrote: >> Since you wanted to develop/port your own device driver anyway, I >> just suggested to use JACK as an interface with your >> applications, instead of the ALSA interface. I believe that the >> JACK API/interface is better suited for realtime applications. >> So why not develop your own new JACK hard-realtime backend with >> your RTDM driver? > I just wanted to modify an existing driver Intel8x0 AC97 to do realtime > playback of a sample. I'm still pursuing this. > I have implemented a regular Linux userspace application for this at first and > it provides a response latency smaller than 1 ms for 19 out of 20 triggers, > but the 20th (on average) has latencies up to 20ms, which is totally > unacceptable. Linux should be able to do better than that. Is your application prioritized properly (check for real-time priorities with "man sched_setscheduler")? And the kernel option CONFIG_PREEMPT should also help. Wolfgang.