On Thu, 18 Dec 2025 17:15:35 GMT, Mikhail Ablakatov <[email protected]> wrote:
>> Wouldn't it be better to move the whole CodeBlob header out of the code >> cache? Instead of nmethod having a _hdr pointer, CodeBlob would be in >> malloc space and have a _code pointer into the CodeCache. > >> Wouldn't it be better to move the whole CodeBlob header out of the code >> cache? Instead of nmethod having a _hdr pointer, CodeBlob would be in malloc >> space and have a _code pointer into the CodeCache. > > It might be possible to move both `CodeBlob` and `nmethod` data to the > C-heap. We'd still need something like an `_hdr` pointer, since JVM resolves > a `CodeBlob` from a method/stub entry point using [`CodeBlob* > CodeCache::find_blob(void* > start)`](https://github.com/openjdk/jdk/blob/7a7e7c9ae11cb124c14d5d2d3b7e2f5649205106/src/hotspot/share/code/codeCache.cpp#L640). > So if we move every member field to the C-heap, we store a pointer to that > data right before a method/stub entry point in the CodeCache and that's it. A > `_code` pointer pointing from the C-heap into the CodeCache may not be > necessary at all. > > That said, this would require moving data for other `CodeBlob` subclasses > (`AdapterBlob`, `ExceptionBlob`, etc.) to the C-heap, which would > significantly broaden the scope of this patch. > > @Bhavana-Kilambi , what do you thing? Is this something you've considered? @mikabl-arm do you have any performance results to show effect of these changes? You added a lot of indirect loads. ------------- PR Comment: https://git.openjdk.org/jdk/pull/28866#issuecomment-3886114645
