Improve reporting of inlined frames about perf-map-agent HOT 12 CLOSED

Yes, that's something I'd like to do as well. I wonder if it makes sense at all to rely on the perf user-space tools to do the symbol lookup or if it wouldn't make more sense to implement the expansion in an extra tool.

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It adds up to much the same process perf is doing anyhow, matching a range of addresses to a string. There's an optimization to be had by logging the jmethodIds rather than the long string they represent. That might be helpful for FlameGraph tooling, but will not help perf-top etc.

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Yes, but this is slightly different as we match one address to a whole stack of frames which is nothing that perf tools currently support.

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True, I thought we could just make it a really long string and unwind it in FlameGraphs

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The more I think about it the more I like your simple suggestion.

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Here's a first approximation:

https://github.com/jrudolph/perf-map-agent/tree/w/25-output-all-inlined-frames

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I'm using this branch now for a while and it seems to work basically as intended.

I recently noticed an odd thing, though: it seems that the reported information for addresses which contain inlined code are not as granular as they are reported with PrintAssembly. I haven't yet researched deeply why that would be the case.

FTR here's OpenJDK code which produces the inline info: http://hg.openjdk.java.net/jdk8/jdk8/hotspot/file/87ee5ee27509/src/share/vm/prims/jvmtiExport.cpp#l1716

and here the code which generates code annotations for PrintAssembly: http://hg.openjdk.java.net/jdk8/jdk8/hotspot/file/87ee5ee27509/src/share/vm/code/nmethod.cpp#l2807

The effect of the problem is that the most interesting addresses in a JIT-compiled method that contains all the inlined stuff from other methods are reported as if they belonged to the JIT-compiled method (and not to the inlined ones). On the hand, it seems that code that is generated as the slow fallback will be properly annotated.

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Are you enabling non safepoint debug info?

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No, I wasn't! Adding -XX:+UnlockDiagnosticVMOptions -XX:+DebugNonSafepoints I'll get inlining info for the rest of the addresses as well.

Thanks, @nitsanw.

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a classic :-) catches me out every once in a while too

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Are you planning on merging the branch?

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It's finished from my side, so if anyone wants to have a look, see #35 which I will soon merge.

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