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Rather than DMA mapping and unmapping every outgoing skb, copy the skb into a buffer that was mapped during the drivers open function. Copying the skb and its frags have proven to be more time efficient than mapping and unmapping. As an effect, performance increases by 3-5 Gbits/s. Allocate and DMA map one continuous 64KB buffer at `ndo_open`. This buffer is maintained until `ibmveth_close` is called. This buffer is large enough to hold the largest possible linnear skb. During `ndo_start_xmit`, copy the skb and all of it's frags into the continuous buffer. By manually linnearizing all the socket buffers, time is saved during memcpy as well as more efficient handling in FW. As a result, we no longer need to worry about the firmware limitation of handling a max of 6 frags. So, we only need to maintain 1 descriptor instead of 6 and can hardcode 0 for the other 5 descriptors during h_send_logical_lan. Since, DMA allocation/mapping issues can no longer arise in xmit functions, we can further reduce code size by removing the need for a bounce buffer on DMA errors. Signed-off-by: Nick Child <nnac123@linux.ibm.com> Signed-off-by: David S. Miller <davem@davemloft.net> |
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| crypto | ||
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| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
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| .cocciconfig | ||
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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.