Hi ,all. I had been reading this thread of PREEMPT_RT for a few days. (I miss the starting mails since I can't get to the web page of google groups)
For my situation, I just need my userspace program run once every 1ms sys tick. The result will be writed to a fifo in FPGA to achive realtime IO control. Can this be achive by eanbling PREEMPT ? any other works need? ======== 2014-02-28 16:53:26 您在来信中写道： ======== Thanks for you tips. I am using a minimal Ubuntu system without a full desktop that is based on http://www.armhf.com/index.php/boards/beaglebone-black/#precise. I used apt-get to update the system. The integrated eMMC and HDMI are deactivated. To create a network stress I used Ubuntu's iperf in server mode from another ssh shell while running stress and cyclictest at the same time. The transfer rate to another Ubuntu box reached 94.7 MBit/s and > 100MB were copied. The latency numbers did not change. Am Mittwoch, 26. Februar 2014 16:58:31 UTC+1 schrieb Charles Steinkuehler: Xenomai includes a "dohell" script that can generate disk and network load. You can always just "dd" to a file for a while. If you're running a Debian/Ubuntu based system, I've found that running "aptitude upgrade" if you have a few dated packages can be a major stress to the system. That gets you both network and disk load, and not so long ago had a decent chance of wedging the eMMC kernel driver (even without the Xenomai patches that 'tickled' the eMMC driver bug and made it more likely to happen). Opening GUI programs and moving windows around is another good stress. On 2/26/2014 9:48 AM, [email protected] wrote: > The stress tool generates cpu load only. But it is a good idea to consider > other load scenarios, too. The current test was done using ssh so there was > at least some network activity. Do you know of a good test tool which > allows to generate disk and network load? > > > Am Mittwoch, 26. Februar 2014 15:58:55 UTC+1 schrieb Charles Steinkuehler: >> >> 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] <javascript:> 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 �Ccpu 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] <javascript:> >> > -- 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. 在此邮件中未发现病毒。 检查工具：AVG - www.avg.com 版本：2014.0.4259 / 病毒数据库：3705/7143 - 发布日期：03/02/14 = = = = = = = = = = = = = = = = = = = = = = 致 礼！ Yang [email protected] 2014-03-04 -- 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.
