[lttng-dev] Tagging traces with arbitrary data (as in custommetadata)

[Mathieu Desnoyers]

----- Original Message -----

> From: "David Lindström" <david.lindstrom at percepio.se>
> To: "Mathieu Desnoyers" <mathieu.desnoyers at efficios.com>, "DavidLindström"
> <david.lindstrom at percepio.se>
> Cc: lttng-dev at lists.lttng.org
> Sent: Tuesday, November 5, 2013 9:49:08 AM
> Subject: Re: [lttng-dev] Tagging traces with arbitrary data (as in
> custommetadata)

> > From: Mathieu Desnoyers
> 
> > Sent: Tuesday, November 05, 2013 3:20 PM
> 
> > To: DavidLindström
> 
> > Cc: lttng-dev at lists.lttng.org
> 
> > Subject: Re: [lttng-dev] Tagging traces with arbitrary data (as in
> > custommetadata)
> 
> > ----- Original Message -----
> 

> > > From: "David Lindström" <david.lindstrom at percepio.se>
> > 
> 
> > > To: lttng-dev at lists.lttng.org
> > 
> 
> > > Sent: Tuesday, November 5, 2013 9:15:14 AM
> > 
> 
> > > Subject: [lttng-dev] Tagging traces with arbitrary data (as in custom
> > > metadata)
> > 
> 
> > > Hi, I was wondering if there’s a way to tag a trace with some additional
> > > information. A general example would be to include a description of the
> > > current experiment. One way to do this currently would be to create a
> > > custom
> > > lttng-message application with some UST tracepoint and then just log that
> > > to
> > > a separate channel, but that would be pretty ugly. It would be much
> > > cleaner
> > > to insert extra fields into the metadata stream. Is something like that
> > > possible in current versions of LTTng and/or would it be possible to add
> > > it
> > > for a future version?
> > 
> 

> > The CTF metadata has an environment (env {}) section that contains this
> > kind
> > of information. LTTng already uses it to store the tracer version and some
> > info about the system. We could eventually add a feature like this, a
> > "tag",
> > that would be added to the CTF environment information. I would guess that
> > users would provide this tag on the lttng command line for their session,
> > and it would be passed to the tracers by sessiond.
> 
> > Thoughts ?
> 

> I have no idea how this would be implemented, I’m only looking at potential
> uses. A simple tag field in the env{} section should cover my initial use
> cases. I have to wonder though, how much more complicated it would be to
> allow multiple named tags? For example, tags.description = ”Some
> description” instead of tag = “Some description”?

This could be called "user-provided environment", and could look like this in the metadata: 

env { 
.... 
user.myenvname = "text"; 
} 

> Also, how would one specify this? As an option to the lttng create command or
> as a separate command (lttng set-tag ...)?

lttng set-env "text" 

Thoughts ? 

Thanks, 

Mathieu 

> Mvh
> David Lindström

> > Thanks,
> 
> > Mathieu
> 

> > > Mvh
> > 
> 
> > > David Lindström
> > 
> 

> > > _______________________________________________
> > 
> 
> > > lttng-dev mailing list
> > 
> 
> > > lttng-dev at lists.lttng.org
> > 
> 
> > > http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
> > 
> 

> > --
> 
> > Mathieu Desnoyers
> 
> > EfficiOS Inc.
> 
> > http://www.efficios.com
> 

-- 
Mathieu Desnoyers 
EfficiOS Inc. 
http://www.efficios.com 
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