Re: [ltt-dev] trace a futex

[Mathieu Desnoyers]

* Peter Zijlstra (peterz@xxxxxxxxxxxxx) wrote:
> 
> FWIW, the ftrace infrastructure has on many an occasion (even before it
> was called ftrace and specific to -rt) helped in debugging and fixing
> futex races.
> 

Hrm, I'm not sure futex races is the key aspect of interest here.
Knowing which amount of pthread mutex lock calls ends up calling the
scheduler looks a bit more like the topic brought by this particular
use-case. Therefore, correlating the information from the nptl with the
kernel information would be useful.

Is lockdep called when a futex is taken ? Should we add instrumentation
(tracepoints) to futex.c ? If yes, was there specific instrumentation
you used with ftrace that should be added ?

Mathieu

-- 
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/