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Re: [tor-bugs] #13802 [Tor]: Add instrumentation to tor (was: Add LTTng instrumentation to tor)
#13802: Add instrumentation to tor
--------------------------+------------------------------------------------
Reporter: dgoulet | Owner:
Type: | Status: assigned
enhancement | Milestone: Tor: 0.2.7.x-final
Priority: normal | Version:
Component: Tor | Keywords: SponsorR, 027-triaged-1-deferrable
Resolution: | Parent ID: #13792
Actual Points: |
Points: |
--------------------------+------------------------------------------------
Changes (by dgoulet):
* cc: rob.g.jansen@â (removed)
* cc: robgjansen (added)
Old description:
> Relevant to #13792, we (nickm and I) discussed what would be the way to
> collect and gather those statistics and measurements in a private network
> for performance analysis and debugging.
>
> Using LTTng (https://lttng.org) to gather events of the different
> subsystems of tor (in userspace of course) seems like a good solution.
> This would be completely deactivated at compile time meaning tracepoints
> would be NOP. You would have to explicitly enable that feature during the
> configure process.
>
> We think the best way to go with that, in terms of code, is to go in a
> header with something that could look like this:
>
> {{{
> #ifdef TOR_USE_LTTNG
> tracepoint_aname(arg1, arg2, [...]) tracepoint(aname, arg1, arg2, ...)
> #else
> tracepoint_aname(arg1, arg2, [...])
> #endif
> }}}
>
> The really good thing about this approach is that 1) everything is
> centralized in one place, 2) you NOP the call if not configured thus no
> performance issue, 3) We can support other tool like DTrace or SystemTap
> and possibly Windows tools. It provides a simple way to hook any other
> tool in the trace event facility of the code.
New description:
Relevant to #13792, we (nickm and I) discussed what would be the way to
collect and gather those statistics and measurements in a private network
for performance analysis and debugging.
This would be completely deactivated at compile time meaning tracepoints
would be NOP. You would have to explicitly enable that feature during the
configure process.
We think the best way to go with that, in terms of code, is to go in a
header with something that could look like this:
{{{
#ifdef TOR_USE_LTTNG
tracepoint_aname(arg1, arg2, [...]) tracepoint(aname, arg1, arg2, ...)
#else
tracepoint_aname(arg1, arg2, [...])
#endif
}}}
The really good thing about this approach is that 1) everything is
centralized in one place, 2) you NOP the call if not configured thus no
performance issue, 3) We can support lots of different tracers as well as
shadow. It provides a simple way to hook any other tool in the trace event
facility of the code.
--
--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/13802#comment:9>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online
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