Messages in this thread | | | Date | Thu, 1 Dec 2011 17:15:00 -0500 | From | Mathieu Desnoyers <> | Subject | Re: [PATCH 09/11] sched: export task_prio to GPL modules |
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* Peter Zijlstra (peterz@infradead.org) wrote: > On Thu, 2011-12-01 at 17:04 -0500, Mathieu Desnoyers wrote: > > * Peter Zijlstra (peterz@infradead.org) wrote: > > > On Thu, 2011-12-01 at 16:41 -0500, Mathieu Desnoyers wrote: > > > > LTTng needs this symbol to prepend the current task dynamic priority > > > > value to events (optional context information). > > > > > > I absolutely detest exporting such stuff. It propagates the idea that > > > task prio actually means something. Also, modules really shouldn't care. > > > > People debugging their SCHED_FIFO/SCHED_RR applications, as well as > > users of priority-inheritance futexes, may happen to find this > > information extremely useful. > > > > Just saying... > > Right until the moment we go do deadlines.. Anyway, it still doesn't > make sense, your sched_switch() tracepoint handler gets this > information, why do you need this export at all?
If you don't want to trace sched_switch, but just conveniently prepend this information to all your events, then lttng lets you dynamically target this extra bit of information. Note that it's not a mandatory event field: I call those "context" fields that the tracer prepends to events, as requested by the user.
Thanks,
Mathieu
-- Mathieu Desnoyers Operating System Efficiency R&D Consultant EfficiOS Inc. http://www.efficios.com
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