RFR: 8299748: java/util/zip/Deinflate.java failing on s390x [v2]

[Jaikiran Pai]

On Mon, 6 Mar 2023 13:10:57 GMT, Ilya Leoshkevich <duke at openjdk.org> wrote:

> Here are some benchmarking results: https://github.com/iii-i/zlib-ng/wiki/Performance-with-dfltcc-patch-applied-and-dfltcc-support-built-on-dfltcc-enabled-machine. The interesting data is in column `compressed_size` where `level` is 1. This is the hardware compressed size divided by the software compressed size. Most of the time it's +5-20%, in a few cases it compresses better than software, and only in one case (kennedy.xls) we see a big difference of +44%.
> 
> P.S. Here we are compressing random data, if I read the testcase correctly (`rnd.nextBytes(dataIn);`), so poor results are expected. Ideally we should emit stored blocks, but the hardware engine does not support this at the moment.

Thank you Ilya, that was helpful in understanding the current behaviour of this custom zlib implementation.

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PR: https://git.openjdk.org/jdk/pull/12283