-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 I believe most or all of what you're wanting to do can be implemented using the cpuset commands: https://rt.wiki.kernel.org/index.php/Cpuset_Management_Utility
I didn't see much change in the very limited testing I did with this, but I did not try very many options. On 9/23/2012 2:34 AM, Michael Haberler wrote: > I just stumbled upon an idea (yet untested) to improve latency with > RT_PREEMPT on multicore cpu's like the atom > > this assumes that rtapi_app in sim mode (plus hal_parport in > usermode) will be the time-critical component it borrows from the > isolcpus=1 idea for RTAI where CPU1 would be reserved for the base > thread the idea is to do something similar for rtapi_app: > > quote from: Max Krasnyansky's post in > http://www.digipedia.pl/usenet/thread/19080/11385/ > >> Actually this is kind of available right now with vanilla 2.6 >> kernel. I'm talking about CPU reservation. Here is an example. >> Let's say we have dual CPU box and we want to dedicate CPU 1 to >> our application: - Configure the kernel with following boot >> options: isolcpus=1 acpi_irq_nobalance noirqbalance >> >> This excludes CPU 1 from the scheduler balancing logic. And >> disables ACPI and SW irq balancing. Make sure that you don't run >> user-space IRQ balancer. >> >> - Redirect all interrupts to CPU 0 for i in /proc/irq/*; do echo >> 1 > $i/smp_affinity; done >> >> - Your app call now migrate to CPU 1 int cpu = 1; uint32_t mask = >> (1 << cpu); sched_setaffinity(0, sizeof(mask), (cpu_set_t *) >> &mask); >> >> That's it. CPU 1 is yours. There will be almost zero activity on >> it, besides your task of course. >> >> Max > > what would needed to be done is to add the sched_setaffinity() code > fragment to rtapi_app and do the boot/setup incantations before > starting linuxcnc > > - Michael > > Am 14.09.2012 um 15:46 schrieb Kent A. Reed: > >> Thanks, Jan, Lars, Michael, Charles, Ken, and Steve for your >> thoughts. >> >> I'll have to cogitate a bit on what to do next, but I can answer >> Steve off the top of my head. Two pre-built realtime kernels are >> available from the Debian Wheezy repository. The amd64 build is >> for 64-bit amd and intel processors; there is also a 32-bit >> 3.2.0-3-rt-686-pae build. That's what I alluded to in my third >> agenda item to try. >> >> <muttered aside> Yes, I know I could custom-build my own kernel, >> but there comes a point where I say "enough, this isn't just >> tweaking any more." It took LinuxCNC (well, ok, EMC2) a while to >> get to the point where a LiveCD distribution just works for most >> folk. I'm hoping it doesn't take as long for our use of these >> alternative realtime platforms to stabilize in the same way, >> especially since I believe they are necessary alternatives. If >> using RT PREEMPT or Xenomi approaches requires more than a >> straightforward tuning-your-system checklist, then I don't know >> how we'll make the alternatives attractive to our user base let >> alone attract new classes of users. That would be unfortunate. >> </muttered aside> >> >> It's clear to me from your responses that if I want to run with >> the big dogs I have to learn how to instrument a realtime >> environment :-) >> >> Regards, Kent >> >> >> On 9/14/2012 8:05 AM, Steve Stallings wrote: >>> Hi Kent, >>> >>> I have NO experience with doing this sort of build, but have to >>> wonder if it is significant that your target is an Atom D510 >>> cpu, yet you list a kernel for amd64. >>> >>> Regards, Steve Stallings >>> >>>> -----Original Message----- From: Kent A. Reed >>>> [mailto:kentallanr...@gmail.com] Sent: Thursday, September >>>> 13, 2012 11:31 PM To: EMC developers Subject: >>>> [Emc-developers] question re RT PREEMPT linux on ASUS Atom >>>> board >>>> >>>> >>>> <blah blah blah> >> >> ------------------------------------------------------------------------------ >> >> Got visibility? >> Most devs has no idea what their production app looks like. Find >> out how fast your code is with AppDynamics Lite. >> http://ad.doubleclick.net/clk;262219671;13503038;y? >> http://info.appdynamics.com/FreeJavaPerformanceDownload.html >> _______________________________________________ Emc-developers >> mailing list Emc-developers@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/emc-developers > > > ------------------------------------------------------------------------------ > > Everyone hates slow websites. So do we. > Make your web apps faster with AppDynamics Download AppDynamics > Lite for free today: > http://ad.doubleclick.net/clk;258768047;13503038;j? > http://info.appdynamics.com/FreeJavaPerformanceDownload.html > _______________________________________________ Emc-developers > mailing list Emc-developers@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-developers - -- Charles Steinkuehler char...@steinkuehler.net -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAlBgSmYACgkQLywbqEHdNFxLZQCfbpSy4XMrl8vd6HjAVf0ZSSHu MI4An1Gu++Xcl7ieYCUl0plsBMgA09L1 =u//g -----END PGP SIGNATURE----- ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. 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