From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <50AA3732.5000701@xenomai.org>
Date: Mon, 19 Nov 2012 14:42:10 +0100
From: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
MIME-Version: 1.0
References: <CAL7_A_WEXhEBQr+LFb_mfaqLxBh=hsHJg6WiY08cmkgb=Y2TNA@mail.gmail.com>	<4FF369E5.5040007@xenomai.org>	<CAL7_A_WYVjFhh9RuxAm1jtVp7HqakB5gEzkSt8i7XsWJNJrh=Q@mail.gmail.com>	<4FF402AD.3020601@xenomai.org>	<4FF415AB.2030503@xenomai.org>	<CAL7_A_Xr432pEEEiG4D5xsD-2yqWdgSd0tD26aEi4q0FzeWD_w@mail.gmail.com>	<CAL7_A_XMD_KY9nryEyb3xzHpCb1PFYTG6qJupLWqRZhJXjkYRw@mail.gmail.com>	<4FF44389.3030209@xenomai.org>	<CAL7_A_WTJUeWNTTra2t9veiyWMxC5VtpotocMHGPdU1v7QAxKA@mail.gmail.com>	<4FF44C52.6050809@xenomai.org>	<CAL7_A_VUC8JD9yeMnLt2iJQ0ex_at3QMhiL3cQ5CHPFh0rcJRA@mail.gmail.com>	<4FF585C4.1000708@xenomai.org>
	<CAL7_A_WZ=mQ9F_Od92qQKFS85QcOtOwqyXu+omrhOBgnZpJFNQ@mail.gmail.com>
In-Reply-To: <CAL7_A_WZ=mQ9F_Od92qQKFS85QcOtOwqyXu+omrhOBgnZpJFNQ@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: 8bit
Subject: Re: [Xenomai] Xenomai and normal linux application - Wait time with
 select() not reliable
List-Id: Discussions about the Xenomai project <xenomai.xenomai.org>
List-Unsubscribe: <http://www.xenomai.org/mailman/options/xenomai>,
	<mailto:xenomai-request@xenomai.org?subject=unsubscribe>
List-Archive: <http://www.xenomai.org/pipermail/xenomai>
List-Post: <mailto:xenomai@xenomai.org>
List-Help: <mailto:xenomai-request@xenomai.org?subject=help>
List-Subscribe: <http://www.xenomai.org/mailman/listinfo/xenomai>,
	<mailto:xenomai-request@xenomai.org?subject=subscribe>
To: =?UTF-8?B?SmVucyBLw7ZobGVy?= <jenskxxx@googlemail.com>
Cc: xenomai@xenomai.org

On 11/19/2012 02:29 PM, Jens Köhler wrote:
> Hello,
> 
> Now is Xenomai 2.6 installed. But I have sometimes still delays in
> user space applications.
> 
> Delay: 0.003064
> Delay: 0.003066
> Delay: 0.003504
> Delay: 0.003066
> Delay: 0.003066
> Delay: 0.003066
> Delay: 0.003090
> Delay: 0.003064
> Delay: 0.003066
> Delay: 0.003067
> Delay: 0.053807 <- 53 ms instead 3ms
> Delay: 0.003067
> Delay: 0.003067
> 
> I found out that problem depends from a real time queue between two
> Xenomai tasks.
> 
> retval = rt_queue_create(&RtMeasureData, "RtMeasureData", 1000 * 256,
> Q_UNLIMITED, Q_FIFO | Q_SHARED);
> 
> A real time task writes measurement data every 2 ms to a rt_queue.
> retval = rt_queue_write(&RtMeasureData, &FifoMeasureData, 256, Q_NORMAL);
> 
> Another Xenomai task reads all measured data from queue and makes them
> available for user land applications. (Task is not real time, context
> switches)
> 
> retval = rt_queue_read(&RtMeasureData, &FifoMeasureData, 256, TM_NONBLOCK);
> 
> When nothing is written to queue is there also never an unexpected delay.
> 
> Any ideas or recommendations to find reason for problem?

Without seeing any code, there is strictly nothing we can do.
If you are able to reduce the code to a simple, self-contained test case
we can run anywhere, then we can have a look at it.
If not, then use the I-pipe tracer.

-- 
					    Gilles.