> Datum: 31/10/07 01:17 AM > Van: "Steven Rostedt" > Aan: "Gerrit Binnenmars" > CC: linux-rt-users@xxxxxxxxxxxxxxx > Onderwerp : Re: CONFIG_CRITICAL_IRQSOFF_TIMING > > > -- > On Tue, 30 Oct 2007, Gerrit Binnenmars wrote: > > > > Datum: 29/10/07 02:09 PM > > > Van: "Steven Rostedt" > > > Aan: "Gerrit Binnenmars" > > > CC: linux-rt-users@xxxxxxxxxxxxxxx > > > Onderwerp : Re: CONFIG_CRITICAL_IRQSOFF_TIMING > > > > > > > > > -- > > > On Sun, 28 Oct 2007, Gerrit Binnenmars wrote: > > > > > > > Hello, > > > > > > > > Can someone send me a .config file that shows the options needed to get the interrupt off > > > > timing values in preempt_max_latency, please. I only see a value of 0 in this file > > > > I am using kernel 2.6.22.1 with the corresponding rt patch. > > > > > > > > Thanks in advance, > > > > > > Make sure you have event trace and latency tracing as well as > > > "Interrupts-off critical section latency timing". > > > > > > Then you need to echo 0 > /proc/sys/kernel/preempt_max_latency. > > > > > Hello Steve, > > > > Thanks for your quick response, but the preempt_max_latency remains 0. Also the latency_hist shows no samples taken. > > Can you or someone else have a look at the corresponding CONFIG options? > > > > CONFIG_LTT_PROBE_LOCKING=m > > # CONFIG_LTT_PROBE_STACK is not set > > > > # > > # Kernel hacking > > # > > [...] > > > CONFIG_INTERRUPT_OFF_HIST=y > > CONFIG_CRITICAL_LATENCY_HIST=y > > CONFIG_LATENCY_HIST=y > > Turn off all histograms. They will kill any measurements you are taking. > And yes, you will not get the output from latency_trace that you are > after. Steven and Daniel, I tried your suggestion with the following resulsts: CRITICAL_IRQSOFF_TIMING: preempt_max_latency remains 0 even under load, cyclictest -b is able to store a trace in /proc/latency_trace CRITICAL_PREEMPT_TIMING: kernel won´t start at all (vmlinuz is read from tftp server but nothing afterwards) WAKEUP_TIMING: is working as expected. So switching off the histograms is an improvement. For the moment, I can live with this situation (especially the cyclictest -b option is very useful), but I wonder if anyone else has the same problems? Regards, Gerrit > > -- Steve > > - > 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 > > - 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