On Tue, 2012-09-11 at 13:38 +0200, Wolfgang Wallner wrote: > Hello all, > > I have a few questions about the logging entry "sched: RT throttling > activated" which I observe, and hope this is the correct place to > ask :) > I will start by describing how i come to see this logging entry: > > I use an industrial PC with an 2.6.33 RT PREEMP kernel to run a real > time application (based on the openPOWERLINK stack [1]), which > consists of a kernel part and a user space part. > My application uses the openPOWERLINK stack to exchange data with > other real time nodes in the network (a good overview how this is done > is given on wikipedia [2]). > > When I let my application run overnight, I always see that it stops > working after some hours, and the output of dmesg shows the following: > > [ 622.722690] EdrvInitOne waiting for link up... > [ 624.439269] EdrvInitOne finished with 0 > [ 624.439334] EdrvInit local MAC = 00 60 65 06 B2 25 > [ 624.454662] EplApiProcessImageAlloc: Alloc(640, 1100, 2, 2) > [ 624.454672] EplApiProcessImageAlloc: Alloc(eeea2000, 640, eef36800, > 1100) > [ 624.477242] ifconfig epl 192.168.100.240 returned 0 > [ 635.058012] epl: no IPv6 routers present > [60382.945209] sched: RT throttling activated > [60382.945209] EplTimerHighResk: Continuous timer (handle 0x10000001) > had to skip 836 interval(s)! Likely realtime task went gaga. Kernel or userspace doesn't matter. > My questions are now: > > * What does this logging entry mean? > Could you please point me to some information about RT throttling > so that I can understand what's it about? With stock settings, it means realtime task[s] consumed > 95% of the throttle interval (1s), so the throttle activated, allowing SCHED_NORMAL tasks to have a sip of CPU, to let you try to save the box from nutty RT CPU hogs. See kernel/sched_rt.c. > > * How to debug this issue? > At the moment I don't know what is cause and what is effect. > I'm not sure if I have a misconfiguration somewhere on my linux system > and this influences my application or vice versa. > > Any tips on how to find out what's going on are greatly appreciated :) Hm, I would revoke godlike powers until the recipients can be trusted to use them wisely. 100% CPU utilization being considered highly unwise. -Mike -- 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
