From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <45EFE384.1070602@domain.hid> Date: Thu, 08 Mar 2007 11:20:52 +0100 From: Steven Scholz MIME-Version: 1.0 Subject: Re: [Xenomai-core] xenomai preempting interrupt handler ? References: <45EFD796.7050002@domain.hid> <1173346938.17515.16.camel@domain.hid> <45EFE089.9000508@domain.hid> <1173349157.17515.19.camel@domain.hid> In-Reply-To: <1173349157.17515.19.camel@domain.hid> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable List-Id: "Xenomai life and development \(bug reports, patches, discussions\)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: rpm@xenomai.org Cc: Xenomai-core@domain.hid Philippe Gerum wrote: > On Thu, 2007-03-08 at 11:08 +0100, Steven Scholz wrote: >> Philippe, >> >>>> using an oscilloscope I found that the AT91RM9200 spends up to 300=B5= s 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? >>> Hw interrupts are forcibly enabled before entering any Linux IRQ >>> handler, exactely to prevent the issue you described (e.g. fiddling w= ith >>> an IDE controller in PIO mode also gives funky latency results unless >>> the latter is true), so the answer is yes. >> Thanks. >> >>>> Thus will the duration of the >>>> ethernet interrupt handler add the the worst case latency? >>> 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. >> How could I check this using the tracer? Small hint please? >=20 > http://www.xenomai.org/index.php/I-pipe:Tracer I know this. But I was asking how I could use it to check the above probl= em. Is "Trace IRQs-off times CONFIG_IPIPE_TRACE_IRQSOFF ... Instrument each disable and re-enable of hardware IRQs. This allows to identify the longe= st path in a system with IRQs disabled." the important stuff? -- Steven