[Ocfs2-devel] [PATCH 0/2] ocfs2: add trace event support for ocfs2

[TaoMa]

Joel Becker wrote:
> On Thu, Oct 15, 2009 at 11:05:45AM +0800, Tao Ma wrote:
>   
>> Hi Joel/Wengang,
>>
>> Joel Becker wrote:
>>     
>>> On Thu, Sep 17, 2009 at 06:19:44AM +0800, Wengang Wang wrote:
>>>       
>>>> following patches add trace event support for ocfs2.
>>>>         
>>> Wengang,
>>> 	This looks like a nice start.  Thank you for getting this going.
>>> I'm sorry I haven't gotten back until now, I've been busy.
>>> 	What I'd like to do next is get a small starting set of
>>> tracepoints.  You have one tracepoint in this patch as a good example,
>>> but we should get a few more.  I don't want every mlog changed into a
>>> tracepoint.  Some of them are old and useless :-)  Instead, I'd like to
>>> find information we often want while debugging.
>>> 	Tao, Tiger, and Sunil, what are parts of the code you often come
>>> across when debugging?  Certain mlog() prints you always find really
>>> important to see.  If you point them out, Wengang can cook up
>>> tracepoints for them.
>>>       
>> aops.c maybe? And recovery/dlm(The most awesome part)?
>>     
>
> 	But what things?  We're not just going to replace every mlog,
> and we're not going to do every function.  We really want to figure out
> what information is actually useful and add tracepoints for it.  So if
> you have particular functions you need data on, or particular mlog()
> calls you always like to see, we'd love to hear about it.
>   
No idea of recovery/dlm since I don't have much experience in it.
As for aops.c, I think the most important part is ocfs2_write_begin_no_lock.
It is very complicated, sometimes it will write inline_data, sometimes 
CoW a refcount record, sometimes makes a extent written. It is helpful 
for us to know some detail information about it.

Regards,
Tao
> 	Wengang, dlmglue.c is definitely a place to look at.  I'd love
> to see events for the inc/dec of l_ro_holders and l_ex_holders.  I'd
> also love to see the mlogs for 'BAST fired' and 'UNLOCK AST fired'
> converted, and a similar event for the regular AST.
>
> Joel
>
>