Those are pretty good numbers. Did you have heavy network and disk (uSD/eMMC) load going as well? IIRC, the uSD/eMMC driver was responsible for the worst of the latency spikes I saw, but that's been some time ago and based on the OMAP kernel list traffic, it appears there have been lots of improvements to that code.
On 2/26/2014 7:53 AM, [email protected] wrote: > > > I have recently tested kernel 3.8.13-rt9 ( > https://github.com/beagleboard/kernel/tree/3.8-rt) using > git://git.kernel.org/pub/scm/linux/kernel/git/clrkwllms/rt-tests.git. I am > using Ubuntu 12.04.4. The load was created using stress –cpu 1 which > generates a cpu load of about 100%. I then used cyclictest: > > > root@ubuntu-armhf:/home/ubuntu/rt-tests# ./cyclictest -l1000000 -m -n -t1 > -p99 -i400 -q > > # /dev/cpu_dma_latency set to 0us > > T: 0 ( 770) P:99 I:400 C:1000000 Min: 14 Act: 19 Avg: 18 Max: 132 > > > uname -a reports: > > root@ubuntu-armhf:/home/ubuntu/rt-tests# uname -a > > Linux ubuntu-armhf 3.8.13-rt9-00899-g160e771 #1 SMP PREEMPT Wed Jun 19 > 10:49:36 CEST 2013 armv7l armv7l armv7l GNU/Linux > > > I am absolutely surprised that the result is looking that good. > > > > Am Freitag, 21. Februar 2014 09:20:39 UTC+1 schrieb [email protected]: >> >> I am trying to figure out how to create a kernel for the BBB that supports >> PREEMPT_RT. It's kind of strange that the BBB's default kernel does not >> even have PREEMPT activated. Such a board doesn't fit to many embedded >> applications where we need at least some kind of determinism. It is even >> worse, that nobody seems to care about this problem. Contrary to that, the >> Raspberry PI's standard kernel has PREEMPT activacted from the very >> beginning. >> >> I have tested Robert Nelsons kernel 3.8.13-r9 ( >> https://github.com/beagleboard/kernel/tree/3.8-rt). It does not have >> PREEMPT_RT activated by default. When doing so, it does not boot. But >> activating PREEMPT does work. However, development of this branch has >> stopped several months ago. The official source for RT Linux (3.8.13) has >> evolved since then. Meanwhile there's an rt17 patch set ( >> https://www.kernel.org/pub/linux/kernel/projects/rt/3.8/). Did anybody >> give this a try? Does it work with the BBB? >> >> >> > -- Charles Steinkuehler [email protected] -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/groups/opt_out.
