On 2009-09-08, Hans-Peter Bock <Hans-Peter.Bock@xxxxxxxxxxxxxxxxxxxx> wrote: >> 2. What are the rt-priorities for your application (including the UIO >> thread) and for the network stack threads? >> $ ps -Alm > > The process "geos" is using the uio_sercos3 driver. > > F S UID PID PPID C PRI NI ADDR SZ WCHAN TTY TIME CMD ... > 1 - 0 3 2 0 - - - 0 - ? 00:00:00 migration/0 > 1 S 0 - - 0 -40 - - - migrat - 00:00:00 - > 5 - 0 4 2 0 - - - 0 - ? 00:00:00 sirq-high/0 > 5 S 0 - - 0 10 - - - ksofti - 00:00:00 - > 5 - 0 5 2 0 - - - 0 - ? 00:00:00 sirq-timer/0 > 5 S 0 - - 0 10 - - - ksofti - 00:00:00 - > 5 - 0 6 2 0 - - - 0 - ? 00:00:00 sirq-net-tx/0 > 5 S 0 - - 0 10 - - - ksofti - 00:00:00 - > 5 - 0 7 2 0 - - - 0 - ? 00:00:00 sirq-net-rx/0 > 5 S 0 - - 0 10 - - - ksofti - 00:00:00 - > 5 - 0 8 2 0 - - - 0 - ? 00:00:00 sirq-block/0 > 5 S 0 - - 0 10 - - - ksofti - 00:00:00 - > 5 - 0 9 2 0 - - - 0 - ? 00:00:00 sirq-tasklet/0 > 5 S 0 - - 0 10 - - - ksofti - 00:00:00 - > 5 - 0 10 2 0 - - - 0 - ? 00:00:00 sirq-sched/0 > 5 S 0 - - 0 10 - - - ksofti - 00:00:00 - > 5 - 0 11 2 0 - - - 0 - ? 00:00:00 sirq-hrtimer/0 > 5 S 0 - - 0 10 - - - ksofti - 00:00:00 - > 5 - 0 12 2 0 - - - 0 - ? 00:00:00 sirq-rcu/0 > 5 S 0 - - 0 10 - - - ksofti - 00:00:00 - > 1 - 0 13 2 0 - - - 0 - ? 00:00:00 posixcputmr/0 > 1 S 0 - - 0 -40 - - - posix_ - 00:00:00 - > 5 - 0 14 2 0 - - - 0 - ? 00:00:00 watchdog/0 > 5 S 0 - - 0 -40 - - - watchd - 00:00:00 - ... > 7 - 0 1576 2 0 - - - 0 - ? 00:00:00 IRQ-17 > 7 S 0 - - 0 9 - - - irqd - 00:00:00 - ... > 7 - 0 2196 2 0 - - - 0 - ? 00:00:00 IRQ-16 > 7 S 0 - - 0 9 - - - irqd - 00:00:00 - ... > 4 - 0 2229 2212 0 - - - 22379 - pts/0 00:00:00 geos > 4 S 0 - - 0 -40 - - - futex_ - 00:00:00 - > 5 S 0 - - 0 -30 - - - uio_re - 00:00:00 - Your network stack threads have a priority of 49. The network interrupt thread (IRQ-17) has a priority of 50. The sercos interrupt thread (IRQ-16) also has a priority of 50. Your geos UIO thread has a priority of 89. And another geos thread (most likely the one executing the main sercos driver logic) has the highest priority possible: 99! I don't know exactly what your geos threads are doing, but I suspect that they are the cause. Try reducing the priority of the non-UIO application thread. I do not know why it should have a higher priority than the UIO thread. (Is there ever a reason to run an application at the same priority as such important processes as the watchdog?) If reducing the priority below that of the UIO thread does not help, consider reducing the priority below that of the network stack (<49). If your application is more important that any network activity, then you would not want to do this. But for now it would be helpful to identify if the non-UIO thread is really at fault here. >> 3. How many interrupts per second (approx.) are being generated by >> the Sercos hardware while your application is running? >> $ cat /proc/interrupts; sleep 1; cat /proc/interrupts > > The SERCOS III master runs a cycle time of 2ms, that should be 500 > interrupts per second: > > CPU0 CPU1 > 16: 26948 0 IO-APIC-fasteoi Sercos_III_PCI > LOC: 129961 98461 Local timer interrupts > > CPU0 CPU1 > 16: 27448 0 IO-APIC-fasteoi Sercos_III_PCI > LOC: 130597 99473 Local timer interrupts Indeed. There are also over 500 timer interrupts per second, so I assume that your non-UIO geos thread is using a 2ms timer to perform the sercos driver duties. >> 4. What is the system load while your application is running and when >> the network stops working? >> $ cat /proc/loadavg > > The system is idle: > > 0.01 0.02 0.00 1/114 2374 Was this after the application was running for a few minutes? This surprises me because the reported error implies that the network isn't getting properly scheduled. John Ogness -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
