[ltt-dev] lttv core

[Mathieu Desnoyers]

* Andy Howell (AndyHowell at raitechnology.com) wrote:
> Pierre-Marc Fournier wrote:
>> Andy Howell wrote:
>>> Hello,
>>>
>>>     I have a trace that is causing problems. The gui comes up ok, but
>>> when I zoom in, it dies with:
>>>
>>> ** (lttv.real:32675): CRITICAL **: unknown state : (null)
>>> **
>>> ** ERROR:(eventhooks.c:273):prepare_s_e_line: assertion failed: (FALSE)
>>>
>>
>> Are there lost events in the trace? This is seen in dmesg after
>> recording it or in the lttv console output.
>>
>
> Pierre-Marc,
>
> 	Yes, dmesg shows:
>
> LTT state dump thread start
> LTT state dump end
> LTT : fs : 84072 events lost in fs channel (cpu 1).
> LTT : fs : 660398 events lost in fs channel (cpu 0).
> LTT : vm_state : 8264 events lost in vm_state channel (cpu 1).
>
> I didn't notice the fs ones before. I'm looking at performance issues in 
> my code, so the machine is maxed out.
>
> I made a copy of the trace and removed the fs files. I can zoom in and 
> out with no problems now.
>
> I do see a bunch of warnings, which I assume are harmless:
>
> ** (lttv.real:9974): WARNING **: Cannot find pin_in in schedchange 27677
>
> ** (lttv.real:9974): WARNING **: No channel for marker named block._blk_request_complete found
> ** (lttv.real:9974): WARNING **: No channel for marker named block._blk_request_issue found
> ** (lttv.real:9974): WARNING **: No channel for marker named fs.exec found
> ** (lttv.real:9974): WARNING **: No channel for marker named userspace.function_exit found
> ** (lttv.real:9974): WARNING **: No channel for marker named userspace.thread_brand found
>

In this case, it would probably be better if you unselect the fs/*
events using the debugfs/ltt/markers "enable" files" (echo 0 > enable)
before you gather your trace.

This way you could specifically select the few events you might want to
keep, like the "fs/exec" event, which is needed to show the process
names.

Mathieu
>
>
> Thanks,
>
> 	Andy
>
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-- 
Mathieu Desnoyers
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