On 07/11/2013 01:11 PM, Peter Zijlstra wrote: > On Thu, Jul 11, 2013 at 12:59:32PM -0400, Steven Rostedt wrote: >> On Thu, 2013-07-11 at 12:55 -0400, Steven Rostedt wrote: >> >>>> >>>> Other than that, a function tracer environment that is safer to use might >>>> be >>>> useful for other people as well. >>> >>> Not sure how to make the environment safe, as the main purpose of the >>> function trace is to debug those hard to debug locations, like NMIs, >>> RCU, dynamic ticks, etc. To ensure a "safe" environment, it would >>> cripple the tracer. >>> >>> Hmm, what would you state as a safe environment? How can we detect if >>> the environment is safe to trace or not? >> >> Maybe I misunderstood you. You mean to have this environment be >> something for not just perf, and have the macro be: >> >> NONSAFE_TRACE(__local_bh_enable); >> >> ? >> >> Then, any ftrace user could set a flag in the registering of its ops to >> 'safe_only_functions'. And it will ignore all of these locations. >> There's really not many of them, so it may not be too hard to weed out. > > Yah, like that. But that doesn't invalidate your question as to what 'safe' > would encompass. I think RCU/lockdep would be the big thing for perf, not > sure it should be wider than that.
Ping? There was no conclusion here and this issue is still ongoing in -next. Thanks, Sasha -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
