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Cache demangling step #483

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r1viollet opened this issue Jan 16, 2024 · 5 comments
Closed

Cache demangling step #483

r1viollet opened this issue Jan 16, 2024 · 5 comments

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@r1viollet
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Context

The demangling step is done on the fly after retrieving the symbols from the cache.
This implies extra CPU costs when requesting demangled symbols.

Proposed solution

Add a demangled symbol entry within the caching structure.
@danielocfb
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I am unsure about this one, to be honest. Yes, there could be some CPU gains to be had, but memory overhead is potentially close to unbounded. I haven't heard of anybody caching demangling results (though that doesn't have to mean much).

Given that the demangling is basically the last step of symbolization, could you built that on top instead? I.e., instruct blazesym to not demangle and then demangle yourself based on a cache. That, or longer term we could perhaps come up with some plug-in caching scheme, where you'd be able to configure the Symbolizer at creation time.

@r1viollet
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Agreed.
This is what I did for now and it was OK. The docs around demangling options could maybe mention this.

Thanks for considering. Great library, simple APIs!

@r1viollet
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Proposal for an extra line in the comment over the APIs

    /// The demangling step is not cached (this can have impacts
    /// on performances).

@d-e-s-o
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d-e-s-o commented Jan 17, 2024

Good point. Will incorporate your suggestion. Thanks!

d-e-s-o added a commit to d-e-s-o/blazesym that referenced this issue Jan 17, 2024
@d-e-s-o
Add note about demangling results not being cached
7bfb6cc 
Add a note to the Symbolizer type that it currently does not cache
demangling results.

Refs: libbpf#483
@d-e-s-o d-e-s-o mentioned this issue Jan 17, 2024
Merged
d-e-s-o added a commit to d-e-s-o/blazesym that referenced this issue Jan 17, 2024
@d-e-s-o
Add note about demangling results not being cached
bdb3aff 
Add a note to the Symbolizer type that it currently does not cache
demangling results.

Refs: libbpf#483

Signed-off-by: Daniel Müller <deso@posteo.net>
danielocfb pushed a commit that referenced this issue Jan 17, 2024
@d-e-s-o @danielocfb
Add note about demangling results not being cached
8c2e23f 
Add a note to the Symbolizer type that it currently does not cache
demangling results.

Refs: #483

Signed-off-by: Daniel Müller <deso@posteo.net>
@r1viollet
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Thanks! Closing for now as the caching step is not essential.

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3 participants
@d-e-s-o @r1viollet @danielocfb