[lttng-dev] Enable UST probes only in specific process

Thibault, Daniel Daniel.Thibault at drdc-rddc.gc.ca
Wed Jul 30 12:36:30 EDT 2014

Date: Wed, 30 Jul 2014 17:58:25 +0400
From: Dmitri Shubin <sbn at tbricks.com>

> Is it possible to enable user-space tracepoint in specific process (of given PID)?
> lttng enable-event -u prov:probe --filter '$ctx.vpid==12345'
> enables probe for all processes and then drops unmatched.
> In my case I'm doing rather heavyweight thing in probe (getting stack
> trace) and want to do that only in the process of interest.
> Is it possible?
> The only way I can do it now is playing with LTTNG_HOME variable setting it to different paths for each process.

   I do believe that the filter drops the event before it starts resolving its arguments, so filtering should be enough.  Someone more familiar with the internals of LTTng should set us straight either way.

Daniel U. Thibault
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