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f004f2e535
The FDMA handler is responsible for scheduling a NAPI poll, which will
eventually fetch RX packets from the FDMA queue. Currently, the FDMA
handler is run in a threaded context. For some reason, this kills
performance. Admittedly, I did not do a thorough investigation to see
exactly what causes the issue, however, I noticed that in the other
driver utilizing the same FDMA engine, we run the FDMA handler in hard
IRQ context.
Fix this performance issue, by running the FDMA handler in hard IRQ
context, not deferring any work to a thread.
Prior to this change, the RX UDP performance was:
Interval Transfer Bitrate Jitter
0.00-10.20 sec 44.6 MBytes 36.7 Mbits/sec 0.027 ms
After this change, the rx UDP performance is:
Interval Transfer Bitrate Jitter
0.00-9.12 sec 1.01 GBytes 953 Mbits/sec 0.020 ms
Fixes: 10615907e9 ("net: sparx5: switchdev: adding frame DMA functionality")
Signed-off-by: Daniel Machon <daniel.machon@microchip.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
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https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText 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.