[lttng-dev] Problem with perf:thread in 2.5.0

Thu Jul 24 17:07:57 EDT 2014

On 07/24/2014 04:46 PM, Jonathan Rajotte-Julien wrote:
> 
> Hey Evgeniy,
> 
> 
>> Jonathan, sorry, I've copied wrong output, original command was with perf:thread:cpu-cycles:
>>
>>> lttng add-context -u -t vpid -t perf:thread:cpu-cycles -t perf:thread:instructions -t perf:thread:cache-misses
>> Session auto-20140724-091524 created.
>> Traces will be written in /export/home/eiva/lttng-traces/auto-20140724-091524
>> UST context vpid added to all channels
>> Error: perf:thread:cpu-cycles: UST invalid context
>> Error: perf:thread:instructions: UST invalid context
>> Error: perf:thread:cache-misses: UST invalid context
>> Warning: Some command(s) went wrong
>> UST event eiva_test:* created in channel channel0
> 
> Weird, it works on my side (c&p) with latest version witch is 2.5 stable :P.

I just tested a fresh install from stable ppa (https://launchpad.net/~lttng/+archive/ubuntu/ppa).

and everything seems to work fine. Cycle,cache etc.

Well, keep us up to date.

Cheers
Jonathan

> 
>>
>>> lttng --version
>> lttng (LTTng Trace Control) 2.5.0 - Fumisterie
> 
> From this output I guess you are working with the lttng package and not the source from git. I don't think packaging is the problem here but let just keep that in mind.
> What dist are you on ?
> 
> I'm sure you already done it a thousand time but could you just run these and send the output ?
> 
> First make sure no lttng-sessiond is running then launch:
> 
> lttng-sessiond -vvv
> 
> In a separate terminal:
> 
> lttng destroy -a  // Just in case
> lttng -vvv create test
> 
> lttng -vvv add-context -u -t vpid -t perf:thread:cpu-cycles -t perf:thread:instructions -t perf:thread:cache-misses
> 
> If this work, you could test if you get the data or zero.
> 
> lttng enable-event -u -a -s test 
> 
> lttng start 
> // Run the program
> 
> lttng stop
> 
> Make sure to send the output from lttng-sessiond -vvv.
> 
> 
> Cheers,
> Jonathan
> 
>>
>> Later I've tried cpu-cycles separately and then accidentally switched to perf:cpu. Now everything started to work, but nothing changed since then. Though didn't check if we still get zeroes on another machine.
>>
>>
>> On Thu, Jul 24, 2014 at 7:01 PM, Jonathan Rajotte-Julien <jonathan.rajotte-julien at ericsson.com <mailto:jonathan.rajotte-julien at ericsson.com>> wrote:
>>
>>     Hi!
>>
>>     > Hi!
>>     >
>>     > I use lttng-2.5.0 (tools, modules, …) and linux-3.8.13. When I try to add context for performance counters I get the following error:
>>     >
>>     >> lttng add-context -u -t perf:cpu:cpu-cycles
>>     > Error: perf:cpu:cpu-cycles: UST invalid context
>>     > Warning: Some command(s) went wrong
>>
>>     Well i think we will both agree that the help page does not help very much.(Should fix that)
>>
>>     If we go deep down into the code we get the supported context for UST domain. :)
>>
>>     Ust domain support 6 type of context:
>>     LTTNG_EVENT_CONTEXT_VTID
>>     LTTNG_EVENT_CONTEXT_VPID
>>     LTTNG_UST_CONTEXT_VPID
>>     LTTNG_EVENT_CONTEXT_PTHREAD_ID
>>     LTTNG_EVENT_CONTEXT_PROCNAME
>>     LTTNG_EVENT_CONTEXT_IP
>>     LTTNG_EVENT_CONTEXT_PERF_THREAD_COUNTER
>>
>>     Well this does help a little ... If we dig a little deeper and search around we get more info and see that an enum from "./lttng-tools/include/lttng/event.h" lttng_event_context_t maps to another one in the lttng-tool side ( context_type in add_context.c)
>>
>>     *Important Part*
>>     So if we decrypt the macros and functions in add-context.c, we get that the following contexts are supported for UST:
>>
>>     vpid
>>     vtid
>>     pthread_id
>>     procname
>>     ip
>>
>>     perf:thread:cpu-cycles
>>     perf:thread:cycles
>>     perf:thread:stalled-cycles-frontend
>>     perf:thread:idle-cycles-frontend
>>     perf:thread:stalled-cycles-backend
>>     perf:thread:idle-cycles-backend
>>     perf:thread:instructions
>>     perf:thread:cache-references
>>     perf:thread:cache-misses
>>     perf:thread:branch-instructions
>>     perf:thread:branches
>>     perf:thread:branch-misses
>>     perf:thread:bus-cycles
>>
>>     perf:thread:L1-dcache
>>     perf:thread:L1-icache
>>     perf:thread:LLC
>>     perf:thread:dTLB
>>     perf:thread:iTLB-loads
>>     perf:thread:iTLB-load-misses
>>     perf:thread:branch-loads
>>     perf:thread:branch-load-misses
>>
>>     perf:thread:cpu-clock
>>     perf:thread:task-clock
>>     perf:thread:page-fault
>>     perf:thread:faults
>>     perf:thread:major-faults
>>     perf:thread:minor-faults
>>     perf:thread:context-switches
>>     perf:thread:cs
>>     perf:thread:cpu-migrations
>>     perf:thread:migrations
>>     perf:thread:alignment-faults
>>     perf:thread:emulation-faults
>>
>>     **(TL;DR : perf:cpu:cpu-cycles is not in the list)**
>>
>>     If you want perf:cpu:cpu-cycles you will need a kernel tracing domain.
>>
>>     Even if it make sense that a ust tracing session cannot touch hardware stuff it won’t hurt to be more explicit about it. :).
>>
>>     >
>>     > We have another machine with 2.5.0 (modules are not installed though) and adding perf:cpu:cpu-cycles works fine, but it is always zero in results.
>>
>>     As for this, I cannot explain why lttng-tool does not complain on adding the context.
>>     You can open a bug here http://bugs.lttng.org/projects/lttng-tools (you will need to create an account and sign in)
>>
>>     Cheers,
>>     Jonathan
>>
>>     >
>>     > --
>>     > Cheers,
>>     > Evgeniy
>>     >
>>     >
>>     > _______________________________________________
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>>     > lttng-dev at lists.lttng.org <mailto:lttng-dev at lists.lttng.org>
>>     > http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
>>     >
>>
>>
>>
>>
>> -- 
>> Cheers,
>> Evgeniy
> 
> 
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