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GH-116017: Get rid of _COLD_EXIT - #120960
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I think the number in the README overview of the results is the "HPT" calculation, which (I believe) weights by "noise". You can see that those particular results were pulled upwards by the startup benchmarks, which have a higher standard deviation than most of the others. But yeah, @mdboom can probably explain better. |
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One minor nit, otherwise it looks good.
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The cold exits use quite a bit of memory on JIT builds, and complicate memory allocation improvements (since they are the only immortal, shared-by-all-interpreters, unlinked, un-invalidatable executors). They also introduce a very subtle back-and-forth dance between executors when warming up side exits, and represent a significant proportion of the uops executed.
This:
_EXIT_TRACEinstruction (previously this logic was shared between theexit_to_tracelabel (only used by_EXIT_TRACE) and_COLD_EXIT..._EXIT_TRACEto use anoparginstead of anexit_index...Separately, I added some missing stats to
_DYNAMIC_EXIT.This results in a 34.7% reduction in traces executed, and a 1.6% reduction in uops executed (both corresponding to 3.7 billion fewer
_COLD_EXITS). Per platform:aarch64-apple-darwin: 3% faster, 9% less memoryaarch64-unknown-linux-gnu: 9% faster, 2% less memoryi686-pc-windows-msvc: 3% fasterx86_64-pc-windows-msvc: 3% fasterx86_64-unknown-linux-gnu: 1% faster, 2% less memory