[lttng-dev] make a trace_event in a module (driver)

Jérémie Galarneau jeremie.galarneau at efficios.com
Mon Dec 16 15:33:21 EST 2013


On Mon, Dec 16, 2013 at 12:05 PM, Klaus Dannecker
<klaus.dannecker at gmx.de> wrote:
>
> Am 15.12.2013 23:54, schrieb Francis Giraldeau:
>
>> Le 2013-12-15 13:22, Klaus Dannecker a écrit :
>>>
>>> Hello,
>>>
>>> now its work!
>>> i have download the new lttng-tools. (git pull)
>>>
>>> the next problem:
>>> with
>>> sudo insmod
>>> /lib/modules/3.8.0-29-generic/extra/addons/lttng-trace-events-sample.ko
>>> and
>>> lttng list -k
>>> hurray! i see the new event!
>>
>> Great!
>>
>>> now i start a lttng session and load the trace-events-sample.ko
>>> (compiling the sample in the linux source code)
>>> but i see not the event in the session. (looking in the eclipse viewer)
>>> what i am doing wrong?
>>
>> Could it be possible that the tracepoint is not called? To verify this,
>> I would recommend you to display the information in dmesg just before
>> the tracepoint:
>>
>> if (printk_ratelimit())
>>         printk("hello event!");
>>
>> Then: dmesg -c
>>
>> What does exactly the module is supposed to record?
>
> I see the message "hello event!"
> it does not matter if i start a lttng session or not. I see always the
> message!

Can you see events from the rest of the kernel in your trace?

>
> Regards,
> Klaus
>
>
> Cheers, Francis
>
>
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-- 
Jérémie Galarneau
EfficiOS Inc.
http://www.efficios.com



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