RFR: 6980847: (fs) Files.copy needs to be tuned [v3]

[Alan Bateman]

On Thu, 16 Jun 2022 01:36:09 GMT, Brian Burkhalter <bpb at openjdk.org> wrote:

> It has been observed before that a larger buffer can increase throughput so increasing the minimum transfer size here seems reasonable. I don’t think it would be bad to increase it to 16K. Perhaps do something like the following where `TRANSFER_SIZE` is 16384 instead of 8192

Changing this code to use 16k of stack could have wider impact. I think we should prototype changing UnixCopyFile to use TL buffer cache rather than increasing stack usage or using malloc.

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PR: https://git.openjdk.org/jdk/pull/9161