Am 17.08.2011 11:43, schrieb Oliver Hartkopp: > Am 17.08.2011 10:38, schrieb "Müller, René": >> Hi all, >> >> I have an performance issue with socketcan and an MPC5200B. My setup looks >> like this: >> - MPC5200B board (TQM5200) >> - custom base board with two PCA82C251, one for each can controller >> - linux-2.6.27.18-denx, I use the mpc52xx driver >> - booted with uboot and kernel from flash >> - mount root filesystem via NFS >> - can0 with 1Mbit/s >> - candump -l can0 to tmpfs > > Hi René, > > can you check if the frames are dropped on socket-level? I assume, that the > candump is not able to dump the stuff into tmpfs at full speed. > > See details at: > > http://www.mail-archive.com/[email protected]/msg00170.html
Hi Oliver, thanks for the hint. I tried it, and indeed I lose my frames because I'm to slow with fetching them. I will take a look, if I find a better mechanism to dump the frames. > As this functionality is only working on a 2.6.33+, i created a patch for our > MPC5200 based system (which has a 2.6.28.10), that upgrades the CAN network > and drivers to a recent functionality (including dropcount, isotp, cangw and > a recent mpc52xx driver). > > I can send the (huge) patches to you, if you're interested. Thanks for the offer. For the moment I got a 2.6.35.7 working for testing purposes. If I need a back port later, I will come back to you. Best regards, René > Regards, > Oliver > >> >> Now I play with the busload on can0 (generated by CANalyzer and three >> CANcaseXL). This leads to the following results: >> - 0% to 71% busload -> no missing frames >> - 74% busload -> 5% missing frames >> - 77% busload -> 10% missing frames >> - 90% busload -> 45% missing frames >> >> The missing frames are measured by comparison of the candump log file >> against the CANalyzer log file. The indicated busload is measured by >> CANalyzer. The cause seems to be very simple: the cpu load is too high (or >> the cpu is too slow). When the busload is under 71%, the cpu load is under >> 100%. When the busload goes higher than 71%, the cpu load is 100%. This >> seems to be the cause for the missing frames. >> >> Has anyone else ever seen such an performance issue? Does someone use the >> MPC5200B in high busload environments? Maybe I configured something wrong in >> my linux. >> >> What about lincan? It has an character device approach with very little >> overhead. Is there an chance, that this will solve my problem? >> >> >> Best regards, >> René >> >> _______________________________________________ >> Socketcan-users mailing list >> [email protected] >> https://lists.berlios.de/mailman/listinfo/socketcan-users > > _______________________________________________ > Socketcan-users mailing list > [email protected] > https://lists.berlios.de/mailman/listinfo/socketcan-users _______________________________________________ Socketcan-users mailing list [email protected] https://lists.berlios.de/mailman/listinfo/socketcan-users
