614b4f5d0f
Convert ip_fast_csum() so it doesn't call csum_partial(), but instead open code the checksum calculation. The problem with csum_partial() is that it makes use of the cksm instruction, which has high startup costs and therefore is only very fast if used on larger memory regions. IPv4 headers however are small in size (5-16 32-bit words). The open coded variant calculates the checksum in ~30% of the time compared to the old variant (z14, march=z196). Signed-off-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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.
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.