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On CPM, the RISC core is a lot more efficiant when doing transfers in 16-bits chunks than in 8-bits chunks, but unfortunately the words need to be byte swapped as seen in a previous commit. So, for large tranfers with an even size, allocate a temporary tx buffer and byte-swap data before and after transfer. This change allows setting higher speed for transfer. For instance on an MPC 8xx (CPM1 comms RISC processor), the documentation tells that transfer in byte mode at 1 kbit/s uses 0.200% of CPM load at 25 MHz while a word transfer at the same speed uses 0.032% of CPM load. This means the speed can be 6 times higher in word mode for the same CPM load. For the time being, only do it on CPM1 as there must be a trade-off between the CPM load reduction and the CPU load required to byte swap the data. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Link: https://lore.kernel.org/r/f2e981f20f92dd28983c3949702a09248c23845c.1680371809.git.christophe.leroy@csgroup.eu Signed-off-by: Mark Brown <broonie@kernel.org> |
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| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
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| .clang-format | ||
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| README | ||
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.