On the a somewhat related note, debian wheezy have RT kernels included, just for information I haven't tried it out yet. But it's nice to have prebuilt.
2013/2/20 Michael Haberler <[email protected]>: > > Am 20.02.2013 um 22:07 schrieb Tom Easterday: > >> Let me re-ask the question, for which I gave too much prior information. >> Apologies for that. Are there pre-built packages for RTAI on Ubuntu 12.04 >> Precise? >> -Tom > > no, which was part of the reason for the Xenomai/RT-PREEMPT effort > > but you will very likely be able to run precise with the existing RTAI kernel > just fine by manual installation with dpkg > > - Michael > > >> >> >> >> On Feb 20, 2013, at 3:52 PM, Michael Haberler <[email protected]> wrote: >> >>> Tom, >>> >>> Am 20.02.2013 um 20:29 schrieb Tom Easterday: >>> >>>> I have a problem that looks like either process scheduling, or buffering, >>>> some sort of blocking on a linuxcnc host running 12.04/Xenomai and >>>> 2.6.0pre. It does not display this problem on 10.04/RTAI and 2.6.0pre >>>> (same base hardware, an intel atom board). The symptom is that when >>>> continuously jogging, a DRO showing position on a remote device changes >>>> smoothly when talking to 10.04/rtai. On 12.04/xenomai we get a distinct >>>> pattern of three updates and a pause, three updates and a pause. The >>>> pause is some number of milliseconds long (1/4 second maybe) and >>>> distinctly visible. The remote connection is through our web server >>>> (Rockhopper) over tcp (websocket) on wired ethernet. >>>> >>>> We first thought it was packet buffering or network latency and played >>>> with TCP parameters and system buffers but that had no effect. We put >>>> timing statements in the web server code at the point were we write the >>>> data out and it appears that the whole web server process is being blocked >>>> or something. We tried re-nicing the web server but it didn't help. If >>>> we run Axis locally while doing this it doesn't display this pause, it >>>> moves along smoothly as one would expect. >>>> >>>> For debugging I thought I might try 12.04 and rtai to see if it was just >>>> with the xenomai kernel or if rtai on 12 does it as well. Are there rtai >>>> packages available for 12.04 yet? I was going through the email list >>>> archive on the new RT stuff but don't see any pointer to packages on rtai >>>> specifically... >>>> >>>> Any thoughts on what we might look at to narrow it down further? >>> >>>> From the above I can tell: >>> >>> - you are running some of your own code because you cite some 'web server' >>> which is not part of a released or working branch. Where is the code, the >>> configuration you are using, and the exact sequence of commands leading up >>> to it? >>> - you say you are running '2.6.0pre', whatever that is, that tag isnt a >>> unique identifier. Please state repository, branch name, commit, and which >>> changes you did. >>> - you do not say anything about hardware, exact lan setup including any >>> intermediate hardware, the board, kernel version - how are we supposed to >>> guess? >>> >>> With that level of information, my thought is that you will get zero help >>> in narrowing down things further, simply because it is impossible. >>> >>> -- >>> >>> that said, what I suggest you do is: triage the problem into a) network >>> driver and hardware b) tcp kernel stack and throughput c) application. >>> >>> a) Find throughput tests which measure at the packet loss level with the >>> least kernel intervention, that is - raw throughput tests at the ethernet >>> or UDP level. Find out if there are significant differences between >>> operating systems on the same hardware. Change hubs/switches or whatever >>> have in between. Try a crossover cable. >>> >>> b) do the same including the TCP stack which measures end-to-end throughput >>> at the TCP level. Observe the TCP retransmission numbers in netstat which >>> should give a clue. >>> >>> c) as for application level issues, install wireshark and pcap, and trace >>> the flow between the programs which show the the issue - we dont know which >>> they are since you do not tell. The packet capture will include timestamps >>> and TCP retransmissions which hint at network problems. If you see any >>> retransmissions, try alternate hardware and drivers - this zoo has many >>> animals. Try with everyting on one machine to exclude network issues. >>> >>> And: read this: http://www.chiark.greenend.org.uk/~sgtatham/bugs.html >>> >>> -- >>> >>> One reason why I suggest you produce a more thorough report, and not some >>> ephemeral problem narrative: I spent several hours recently in a off-list >>> debugging session on a 'reported Xenomai problem'. The problem was finally >>> resolved by me demanding to 'yank that ethernet hub *now* and throw it in >>> the wastebin' in no uncertain words. No more Xenomai issues since. Btw that >>> was a device 'which always used to work so far'. So much for perceived >>> causality. >>> >>> >>> - Micahel >>> >>> >>> >>> >>> ------------------------------------------------------------------------------ >>> Everyone hates slow websites. So do we. >>> Make your web apps faster with AppDynamics >>> Download AppDynamics Lite for free today: >>> http://p.sf.net/sfu/appdyn_d2d_feb >>> _______________________________________________ >>> Emc-developers mailing list >>> [email protected] >>> 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://p.sf.net/sfu/appdyn_d2d_feb >> _______________________________________________ >> Emc-developers mailing list >> [email protected] >> 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://p.sf.net/sfu/appdyn_d2d_feb > _______________________________________________ > Emc-developers mailing list > [email protected] > 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://p.sf.net/sfu/appdyn_d2d_feb _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
