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List:       openjdk-serviceability-dev
Subject:    Re: RFR: 8331087: Move immutable nmethod data from CodeCache [v2]
From:       Vladimir Kozlov <kvn () openjdk ! org>
Date:       2024-04-29 16:02:17
Message-ID: Hoe1uvsY0XpRK8tUgukGLjUS0GtbZ8cUcXS55O_C4xg=.11763c09-9b1c-49e9-8200-a4eeed5f1b84 () github ! com
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On Sun, 28 Apr 2024 23:37:22 GMT, Vladimir Kozlov <kvn@openjdk.org> wrote:

> > Move immutable nmethod's data from CodeCache to C heap. It includes \
> > `dependencies, nul_chk_table, handler_table, scopes_pcs, scopes_data, \
> > speculations`. It amounts for about 30% (optimized VM) of space in CodeCache. 
> > Use HotSpot's `os::malloc()` to allocate memory in C heap for immutable nmethod's \
> > data. Call `vm_exit_out_of_memory()` if allocation failed. 
> > Shuffle fields order and change some fields size from 4 to 2 bytes to avoid \
> > nmethod's header size increase. 
> > Tested tier1-5, stress,xcomp
> > 
> > Our performance testing does not show difference.
> > 
> > Example of updated `-XX:+PrintNMethodStatistics` output is in JBS comment.
> 
> Vladimir Kozlov has updated the pull request incrementally with one additional \
> commit since the last revision: 
> Address comments. Moved jvmci_data back to mutable data section.

Thank you, Dean, Doug and Tobias for reviews.

-------------

PR Comment: https://git.openjdk.org/jdk/pull/18984#issuecomment-2083102730


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