[ltt-dev] Traces data alignment

[Mathieu Desnoyers]

* Jérôme Stadelmann (jerome.stadelmann at heig-vd.ch) wrote:
> On vendredi 20 mars 2009 15:53:55 Mathieu Desnoyers wrote:
> > * Jérôme Stadelmann (jerome.stadelmann at heig-vd.ch) wrote:
> > > On jeudi 19 mars 2009 18:00:01 Mathieu Desnoyers wrote:
> > > > * Jérôme Stadelmann (jerome.stadelmann at heig-vd.ch) wrote:
> > > > > Hi everybody,
> > > > > 
> > > > > I'm working on a LTTng traces parser and I'm a little bit blocked on the alignment. Can someone please explain how and where it is coded ?
> > > > 
> > > > The lttv lib "ltttraceread" should do that for you.
> > >  
> > > > > What are the roles of the alignment defined in the traces header and the one defined in the metadata file in the core_marker_id ?
> > > > > 
> > > > 
> > > > They tell that a specific tracefile content is aligned or not, and if
> > > > the content of a given event is aligned or not. You should really have
> > > > at least a look at the ltt lib traceread reference implementation.
> > > 
> > > Thank you. This library helped me a lot. I see that there is an up to 2 byte alignment in the core marker id event definition. Is there the only special case ?
> > > I've searched the uses of the ltt_align function. Are there other functions to look for ?
> > > 
> > 
> > Looking at ltt_align use is a good starting point.
> > 
> > Can you point out to the specific package/version/file/line you refer to
> > for the core marker id "special case" you talk about here ?
> > 
> 
> I think I've understood now. The alignment in the metadata file is
> "hardcoded" as 2 byte because the id field is the biggest value and is
> coded as a 2 bytes value. Am I right ?
> 

Possibly. Again, can you point out which package/version/file/line you
refer to so I can be sure we are talking about the same piece of code ?
Telling which file and function, with a cut and paste of the context,
would be nice to have.

Mathieu

> > Mathieu
> > 
> > > Jerome
> > >  
> > > > Mathieu
> > > > 
> > > > > Regards,
> > > > > Jerome
> > > > > 
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> > > > > 
> > > > 
> > > 
> > 
> 

-- 
Mathieu Desnoyers
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