Messages in this thread | | | Date | Thu, 24 Mar 2016 10:56:48 +0100 | From | Jiri Olsa <> | Subject | Re: [PATCH 2/5] ftrace perf: Move exclude_kernel tracepoint check to init event |
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On Wed, Mar 23, 2016 at 11:41:29AM +0100, Peter Zijlstra wrote: > On Wed, Mar 16, 2016 at 03:34:30PM +0100, Jiri Olsa wrote: > > We suppress events with attr::exclude_kernel set when > > the event is generated, so following capture will > > give no warning but won't produce any data: > > > > $ sudo perf record -e sched:sched_switch:u ls > > $ sudo /perf script | wc -l > > 0 > > > > Checking the attr::exclude_(kernel|user) at the event > > init time and failing right away for tracepoints from > > uprobes/kprobes and native ones: > > > > $ sudo perf record -e sched:sched_switch:u ls > > Error: > > The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (sched:sched_switch). > > /bin/dmesg may provide additional information. > > No CONFIG_PERF_EVENTS=y kernel support configured? > > > > $ sudo perf record -e probe:sys_read:u ls > > Error: > > The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (probe:sys_read). > > /bin/dmesg may provide additional information. > > No CONFIG_PERF_EVENTS=y kernel support configured? > > > > $ ./perf record -e probe_ex:main:k ./ex > > Error: > > The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (probe_ex:main). > > /bin/dmesg may provide additional information. > > No CONFIG_PERF_EVENTS=y kernel support configured? > > Not sure about this one. The previous behaviour suggests > exclude_{user,kernel} is implemented, while the new behaviour says these > flags are not implemented, which is a functional regression.
well I would not expect 'sched:sched_switch:u' to work (be implemented)
and I thought it's better to trigger an error than silently 'produce' no data
> > That is, if all events are from kernel space, and we exclude all kernel > events, 0 is the right answer not an error. > > Sure, with uprobes the situation is currently broken, but this isn't a > fix.
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