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a1b22a5f45
Optimize ChaCha20 NEON performance by: - Implementing the 8-bit rotations using the 'vtbl.8' instruction. - Streamlining the part that adds the original state and XORs the data. - Making some other small tweaks. On ARM Cortex-A7, these optimizations improve ChaCha20 performance from about 12.08 cycles per byte to about 11.37 -- a 5.9% improvement. There is a tradeoff involved with the 'vtbl.8' rotation method since there is at least one CPU (Cortex-A53) where it's not fastest. But it seems to be a better default; see the added comment. Overall, this patch reduces Cortex-A53 performance by less than 0.5%. Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.