RFR: JDK-8180450: secondary_super_cache does not scale well [v5]

[Andrew Haley]

On Fri, 22 Mar 2024 18:20:22 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

> > I would have liked to save the hashed interfaces list in the CDS archive file, but there are test cases for the Serviceability Agent that assume the interfaces are in the order in which they are declared. I think the tests are probably just wrong about this. For the same reason, I have to make copies of the interfaces array and sort the copies, rather than just using the same array at runtime.
> 
> May be file follow up RFE for saving hashed interfaces list in CDS which will also fix those tests.

That sounds good.

> src/hotspot/share/opto/memnode.cpp line 2451:
> 
>> 2449:   }
>> 2450: 
>> 2451:   if (tkls != nullptr && !UseSecondarySuperCache
> 
> May be add comment what are you doing here.
> Is it switching off **current** implementation of secondary super cache optimization or both: current and new?

All it does is switch of the **current** implementation, and only in C2.

> src/hotspot/share/runtime/globals.hpp line 1999:
> 
>> 1997:                                                                             \
>> 1998:   product(bool, UseSecondarySuperCache, true, DIAGNOSTIC,                   \
>> 1999:           "Use secondary super cache during subtype checks")                \
> 
> Is it guard for current implementation or both?

Just the current.

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PR Comment: https://git.openjdk.org/jdk/pull/18309#issuecomment-2015693658
PR Review Comment: https://git.openjdk.org/jdk/pull/18309#discussion_r1536031094
PR Review Comment: https://git.openjdk.org/jdk/pull/18309#discussion_r1536031476