mark probes : usage examples?

mark probes : usage examples?

[Om Narasimhan]

Could anybody point me to some examples for

probe kernel.mark("XX")

Can't find any in the systemtap examples or tapsets.
I would like to know how to identify kernel markers in the kernel source 
code as well.

Thanks,
Om.

Re: mark probes : usage examples?

[Om Narasimhan]

Om Narasimhan wrote:
> Could anybody point me to some examples for
> 
> probe kernel.mark("XX")
> 
> Can't find any in the systemtap examples or tapsets.
> I would like to know how to identify kernel markers in the kernel source 
> code as well.
> 
> Thanks,
> Om.
I think I got the answers.
 From man pages,
probe kernel.mark("getuid")

But I can't see any markers in my kernel source (which is pretty new)
$ pwd
/space/src/linux-exp

$ head -n 5 Makefile
VERSION = 2
PATCHLEVEL = 6
SUBLEVEL = 27
EXTRAVERSION = -rc3
NAME = Rotary Wombat

$ findc | xargs grep -En "STAP_MARK"
$

findc is my function for find . -iname "*.[ch]"

Does it mean that we don't have any markers in kernel source so far?

Thanks,
Om.

Re: mark probes : usage examples?

[Wenji Huang]

Om Narasimhan wrote:
> Om Narasimhan wrote:
>> Could anybody point me to some examples for
>>
>> probe kernel.mark("XX")
>>
>> Can't find any in the systemtap examples or tapsets.
>> I would like to know how to identify kernel markers in the kernel 
>> source code as well.
>>
>> Thanks,
>> Om.
> I think I got the answers.
>  From man pages,
> probe kernel.mark("getuid")
> 
> But I can't see any markers in my kernel source (which is pretty new)
> $ pwd
> /space/src/linux-exp
> 
> $ head -n 5 Makefile
> VERSION = 2
> PATCHLEVEL = 6
> SUBLEVEL = 27
> EXTRAVERSION = -rc3
> NAME = Rotary Wombat
> 
> $ findc | xargs grep -En "STAP_MARK"
> $
> 
> findc is my function for find . -iname "*.[ch]"
> 
> Does it mean that we don't have any markers in kernel source so far?

Yes, marker is the facility which can enable users to define static 
probe point in kernel. Users need to insert trace_mark macro into the 
place where they like.

Currently, there is no well-defined marker points in kernel. Maybe 
later, lttng could be merged into mainline. That will provide some 
built-in ones.

Regards,
Wenji

Re: mark probes : usage examples?

[Frank Ch. Eigler]

Om Narasimhan <om.turyx@gmail.com> writes:

> [...]
> But I can't see any markers in my kernel source (which is pretty new)

You can have systemtap list them for you:
    % stap -l 'kernel.mark("*")'

> $ findc | xargs grep -En "STAP_MARK"
> findc is my function for find . -iname "*.[ch]"

Look for "trace_mark" instead.  There are a few in recent kernels, but
they may have been compiled out with some CONFIG_FOO=n flags.

- FChE