From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: [Xenomai-core] xenomai preempting interrupt handler ? From: Philippe Gerum In-Reply-To: <45EFE089.9000508@domain.hid> References: <45EFD796.7050002@domain.hid> <1173346938.17515.16.camel@domain.hid> <45EFE089.9000508@domain.hid> Content-Type: text/plain; charset="iso-8859-1" Date: Thu, 08 Mar 2007 11:19:17 +0100 Message-Id: <1173349157.17515.19.camel@domain.hid> Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Sender: Philippe Gerum Reply-To: rpm@xenomai.org List-Id: "Xenomai life and development \(bug reports, patches, discussions\)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Steven Scholz Cc: Xenomai-core@domain.hid On Thu, 2007-03-08 at 11:08 +0100, Steven Scholz wrote: > Philippe, >=20 > >> using an oscilloscope I found that the AT91RM9200 spends up to 300=B5s= in the > >> interrupt handler for ethernet controller. > >> > >> Now I wonder if this interrupt handler will be preempted by Xenomai if= there > >> is a high priority, periodic real time task? > >=20 > > Hw interrupts are forcibly enabled before entering any Linux IRQ > > handler, exactely to prevent the issue you described (e.g. fiddling with > > an IDE controller in PIO mode also gives funky latency results unless > > the latter is true), so the answer is yes. > Thanks. >=20 > >> Thus will the duration of the > >> ethernet interrupt handler add the the worst case latency? > >=20 > > Not from Linux IRQ handlers; you may want to check this using the > > tracer. If hw interrupts are masked there, then it's a blatant bug. >=20 > How could I check this using the tracer? Small hint please? http://www.xenomai.org/index.php/I-pipe:Tracer >=20 > Steven --=20 Philippe.