RFR: 8330108: Increase CipherInputStream buffer size

[Anthony Scarpino]

On Sat, 13 Apr 2024 01:25:57 GMT, David Schlosnagle <duke at openjdk.org> wrote:

> Should the buffer size be a configurable constructor parameter? This would allow consumers to adjust the buffer size to match their tradeoffs of memory vs throughput based on workload & available resources, and provide a bit of future-proofing as memory hierarchies expand over time (default 512 byte buffer is a few decades old). I imagine many folks are already wrapping `CipherInputStream` with a `BufferedInputStream` and this would allow folks to adjust the buffer size in `CipherInputStream` and remove the extra wrapper stream.
>

That would involve creating a new constructor and with that comes API change requirements.  If InputStream hasn't supported this feature in the past, I don't think CipherInputStream needs it.
 
> It would be nice to see a broader range of buffer sizes benchmarked across architectures to understand the tradeoffs and differences in throughput. For example, the default `InputStream` buffer size was increased from `8192` to `16384` in JDK-8299336 / #11783 .
> 
> There are also a number of architecture specific tradeoffs related to cipher and intrinsics available that consumers may want to factor into buffer sizing.

The larger the buffer the better in this case.   AES/GCM can take advantage of the bigger buffer on AVX512 systems as it has a 786 byte requirement.   I believe, all the others are blocksize.

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PR Comment: https://git.openjdk.org/jdk/pull/18763#issuecomment-2065332979