On Sun, 17 Jan 2016, Karlsson & Wang wrote: > Date: Sun, 17 Jan 2016 16:37:21 +0100 > From: Karlsson & Wang <nicklas.karls...@karlssonwang.se> > Reply-To: EMC developers <emc-developers@lists.sourceforge.net> > To: Alec Ari <neotheu...@ymail.com> > Cc: emc-developers@lists.sourceforge.net > Subject: Re: [Emc-developers] RTAI ethernet > >> I believe the hostmot2 ethernet drivers only work (or at least have only >> been tested) with PREEMPT_RT. >> >> Alec Ari > > PREEMPT_RT work but it is not possible to put the limit then it come to > period of how often real time tasks could be executed. Without proper > handling of interrupt every now and then there will be a delay by the time > it take to execute the interrupt. I also expect sometimes several will > happen at once and even though it is rare with a machine running several > hours a day it happens sometimes.
Not true at all On Preempt-RT, most hard interrupts are converted to preemptable kernel threads with assignable priorities. On the average, Preempt-RT latency is not quite as good as RTAI but specific versions of Preempt-RT are better than RTAI and Preempt-RT is getting better all the time. I have more than 2 machine years of hm2_eth uptime running under Preempt-RT (with > 1 machine year running at 4 KHz) and have not had any latency issues ( Peak round trip network jitter on the 4 KHz machine is in the 30 usec region over a year of operation and running compiles, youtube videos etc ) > > I run software on microcontrollers with the Cortex-* CPU and sometimes use > the nested interrupt controller as hardware scheduler and get in all essense > perfect real time scheduling. > > Without proper handling of priorities for interrupts it is only possible to > use a rather small percentage of available clock cycles for real time tasks > since delay caused by interrupts must be added to real time tasks execution > time. > > > Nicklas Karlsson > > ------------------------------------------------------------------------------ > Site24x7 APM Insight: Get Deep Visibility into Application Performance > APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month > Monitor end-to-end web transactions and take corrective actions now > Troubleshoot faster and improve end-user experience. Signup Now! > http://pubads.g.doubleclick.net/gampad/clk?id=267308311&iu=/4140 > _______________________________________________ > Emc-developers mailing list > Emc-developers@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-developers > Peter Wallace Mesa Electronics (\__/) (='.'=) This is Bunny. Copy and paste bunny into your (")_(") signature to help him gain world domination. ------------------------------------------------------------------------------ Site24x7 APM Insight: Get Deep Visibility into Application Performance APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month Monitor end-to-end web transactions and take corrective actions now Troubleshoot faster and improve end-user experience. Signup Now! http://pubads.g.doubleclick.net/gampad/clk?id=267308311&iu=/4140 _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
