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0927f71dbc
decrypt_skb fails if the number of sg elements required to map it is greater than MAX_SKB_FRAGS. nsg must always be calculated, but skb_cow_data adds unnecessary memcpy's for the zerocopy case. The new function skb_nsg calculates the number of scatterlist elements required to map the skb without the extra overhead of skb_cow_data. This patch reduces memcpy by 50% on my encrypted NBD benchmarks. Reported-by: Vakul Garg <Vakul.garg@nxp.com> Reviewed-by: Vakul Garg <Vakul.garg@nxp.com> Tested-by: Vakul Garg <Vakul.garg@nxp.com> Signed-off-by: Doron Roberts-Kedes <doronrk@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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.