Increase maximum frames and make maximum tail calls configurable#59
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umanwizard wants to merge 1 commit into
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Increase maximum frames and make maximum tail calls configurable#59umanwizard wants to merge 1 commit into
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umanwizard
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Why not submit this upstream right away? |
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Oh I see the problem is the native unwinder only does 4 frames per invocation. That’s seems low, does doing more frames per program hit the 4K limit? |
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What is the tail call limit in the kernel of concern? |
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@brancz I have. I decided to also submit it to our fork in case the upstream PR takes a while to land. |
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@gnurizen according to the comment, the limit is 32, and we need to reserve a few in order to call UNWIND_STOP. |
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So if we only get 30 invocations of the native unwinder at 4 frames a pop how have we enabled more than 120 frames to be unwound or am I missing something? |
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This PR doesn't actually bump the limit, it just makes it configurable. I will bump the limit in a follow-up PR once this lands. |
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Bump the number of frames in the trace struct to 256, and also make the maximum number of allowed tail calls, so downstream users of the library (e.g. Parca) can choose to support deeper stacks possibly at the cost of not working on older kernels.