Messages in this thread | | | Date | Mon, 17 Nov 2008 19:58:09 +0100 | From | Frederic Weisbecker <> | Subject | Re: [PATCH 2/2] tracing/function-return-tracer: Call prepare_ftrace_return by registers |
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Ingo Molnar a écrit : > * Frédéric Weisbecker <fweisbec@gmail.com> wrote: > >> 2008/11/13 Ingo Molnar <mingo@elte.hu>: >>> hm, function-exit is a quite bad name i think that tells nothing to >>> the user. I like "function-cost tracer" because that tells the user >>> what it's all about in the end. >>> >>> Or perhaps we could name it the "callgraph" tracer? (as opposed to the >>> simpler function tracer which traces function entries) Note that we >>> could use the output to build function call coverage graphs. >> But you can build a call graph with the function tracer, that what >> does the script draw_trace.py in a bit loosely way for example. > > yes, but not reliably so - there's no guaranteed callgraph structure. > With entry tracing we have entry+parent events, but especially across > longer callchains there's no truly guaranteed way to preserve the full > graph.
That's right, with the depth, we could have a more safe result for the call graph.
>> IMHO, function cost measurement or call graphs are particular uses >> that can be made of this engine. You can also use it to trace >> function return values for example. > > yes. The mockup output has place for that.
The problem with this is that we don't know in advance if the return value fits in 32 or 64 bits...
>> So perhaps naming it by thinking on the purpose it could be use at >> most would be better that its "general" or "potential" purpose. I >> don't know... > > i suggested "full-function" tracer name before, but that sounds a bit > quirky too. > > Perhaps this should be the function-tracer, and the entry tracer would > be the function-entry tracer? > > Ingo
I still wonder about the name we should choose... Renaming function to function_entry seems to me a bit wrong because usual function tracing happens in entry...
Why not two-pass function tracer?
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