Hi Tom, On Thu, 05 Apr 2018 18:34:13 -0500 Tom Zanussi <tom.zanussi@xxxxxxxxxxxxxxx> wrote: > Hi Masami, > > On Thu, 2018-04-05 at 12:50 +0900, Masami Hiramatsu wrote: > > [...] > > > Can you print out the error with which event we should see? e.g. > > > > ERROR: Variable already defined at sched_wakeup: ts0 > > > > How about printing the event name along with the last command, for any > error? : > > ERROR: Variable already defined: ts0 > Last command: [sched:sched_wakeup] keys=pid:ts0=common_timestamp.usecs if comm=="cyclictest" Hmm, is the Last command shows the last command on sched_wakeup ? or sched_switch?? [...] > Before: > > # echo 'hist:keys=pid:ts0=common_timestamp.usecs if comm=="cyclictest"' >> /sys/kernel/debug/tracing/events/sched/sched_wakeup/trigger > > # echo '!hist:keys=next_pid:ts0=common_timestamp.usecs if comm=="cyclictest"' >> /sys/kernel/debug/tracing/events/sched/sched_switch/trigger > > And other commands making us think we cleared everything out so the > below error is a surprise > > # echo 'hist:keys=pid:ts0=common_timestamp.usecs if comm=="cyclictest"' >> /sys/kernel/debug/tracing/events/sched/sched_wakeup/trigger > -su: echo: write error: Invalid argument No, my senario is different. Your senario tries 1) define ts0 on sched_wakeup 2) remove ts0 from sched_switch (but silently failed) 3) re-define ts0 on sched_wakeup and get an error In this case, user can dump sched_wakeup/trigger and see there is already ts0 defined. My senario is a bit different 1) define ts0 on sched_wakeup 2) remove ts0 from sched_switch (but silently failed) 3) re-define ts0 on *sched_switch* and get an error The 3rd operation failed on "sched_switch" not on "sched_wakeup". In this case we will totally lost where the ts0 defined. That's why I have asked you to show "where the ts0 is defined" at error line. Anyway, I think it is a good chance to introduce <tracefs>/error_log file, since we have too many non-critical errors on operations. I feel that checking hist file by errors on trigger file is not a bit intuitive. # cat /sys/kernel/debug/tracing/error_log ERROR(events/sched/sched_switch/trigger): Variable already defined: ts0@sched:sched_wakeup Command: keys=pid:ts0=common_timestamp.usecs if comm=="cyclictest" This can be used from probe events too :) e.g. ERROR(kprobe_events): Unsupported type: uint8 Command: p vfs_read arg1=%di:uint8 Any thought? Thank you, -- Masami Hiramatsu <mhiramat@xxxxxxxxxx> -- 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
