Messages in this thread | | | Date | Sat, 16 Sep 2006 01:57:07 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH 0/11] LTTng-core (basic tracing infrastructure) 0.5.108 |
| |
* Nicholas Miell <nmiell@comcast.net> wrote:
> You're going to want to be able to trace every function in the kernel, > which means they'd all need a __trace -- and in that case, a > -fpad-functions-for-tracing gcc option would make more sense then > per-function attributes.
the __trace attribute would be a _specific_ replacement for a _specific_ static markup at the entry of a function. So no, we would not want to add __trace to _every_ function in the kernel: only those which get commonly traced. And note that SystemTap can trace the rest too, just with slighly higher overhead.
In that sense __trace is not an enabling infrastructure, it's a performance tuning infrastructure.
> The option could also insert NOPs before RETs, not just before the > prologue so that function returns are equally easy to trace. (It might > also inhibit tail calls, assuming being able to trace all function > returns is more important than that optimization.)
yeah. __trace_entry and __trace_exit [or both] attributes. Makes sense.
> And SystemTap can already hook into sock_sendmsg() (or any other > function) and examine it's arguments -- all of this GCC extension talk > is just performance enhancement.
yes, yes, yes, exactly!!! Finally someone reads my mails and understands my points. There's hope! ;)
Ingo - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |