On Fri, 2013-04-26 at 11:53 -0500, Jon Elson wrote: > Mark Wendt wrote: > > > > I was thinking more of hardware resources, such as interrupts. What > > happens when both instances require the same interrupt at the same time? > > Unlike shared memory, interrupts are a bit harder to share, or have > > concurrent use. Can the separate instances somehow share the IO bus? Or > > is there some kind of real time scheduler that looks ahead for all possible > > conflicts, and works it out? > > > This has always been a big problem on the PC platform, ie. the extreme > shortage > of interrupt vectors. This is mostly due to an interrupt architecture > that assigns specific bus wires for a single interrupt. Some other > platforms, such as > the ARM, have interrupt requests that provide a bit field to specify the > vector > address (like the PDP-11) where hundreds of vectors can be available. > Just another annoyance on the PC platform. At least on RTAI, there were > some > problems in having regularly scheduled threads running from interrupt lines > instead of the timer. I hope Xenomai or prempt can be more flexible. On my > interface boards, they can sample encoder position and then request an > interrupt > through the parallel port, which would reduce the effect of task latency > on position sampling to zero, as long as the thread completed before the > next interrupt. > > Jon Indeed the pdp-11 did handle interrupts nicely including a cute but rigid priority structure. (daisy-chained down the buss) so you put your highest priority device closest to the cpu.
Too bad Intel didn't have better foresight. D > ------------------------------------------------------------------------------ > Try New Relic Now & We'll Send You this Cool Shirt > New Relic is the only SaaS-based application performance monitoring service > that delivers powerful full stack analytics. Optimize and monitor your > browser, app, & servers with just a few lines of code. Try New Relic > and get this awesome Nerd Life shirt! http://p.sf.net/sfu/newrelic_d2d_apr > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ Try New Relic Now & We'll Send You this Cool Shirt New Relic is the only SaaS-based application performance monitoring service that delivers powerful full stack analytics. Optimize and monitor your browser, app, & servers with just a few lines of code. Try New Relic and get this awesome Nerd Life shirt! http://p.sf.net/sfu/newrelic_d2d_apr _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
