From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <50BC705D.2040407@xenomai.org>
Date: Mon, 03 Dec 2012 10:26:53 +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>	<50AA3732.5000701@xenomai.org>
	<CAL7_A_VBCVX9o4_m4DEH7iDAf423UiowDGy+FhD_VZLcfonq9g@mail.gmail.com>
In-Reply-To: <CAL7_A_VBCVX9o4_m4DEH7iDAf423UiowDGy+FhD_VZLcfonq9g@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: quoted-printable
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 12/03/2012 08:59 AM, Jens K=C3=B6hler wrote:

> Hello,
>=20
> I found following additionaly out:
> One of the Xenomai tasks writes cyclically to a shared linux memory
> (its not a Xenomai shared memory). Write and read access is controlled
> by Linux semaphores. If shared memory writing is out-commented is
> there never a delay problem.


If you expect a task using a Linux semaphore to have bounded latencies,
you misunderstood the way Xenomai works.

>=20
> I found following explanation about Xenomai in internet. Could it
> reason for problem?
>=20
> "If an interrupt arrives while a Xenomai thread executes in secondary
> mode, it is not forwarded to Linux! The mechanism works as follows:
> When a Xenomai thread is executed in secondary mode, the interrupt
> shield domain is activated All Linux interrupts are stalled, until the
> Xenomai thread completes execution. The interrupts will be served
> again when Linux goes back to execute in background mode."


The interrupt shield no longer exists.


--=20
                                                                Gilles.