13511704f8
Even though the taprio qdisc is designed for multiqueue devices, all the queues still point to the same top-level taprio qdisc. This works and is probably required for software taprio, but at least with offload taprio, it has an undesirable side effect: because the whole qdisc is run when a packet has to be sent, it allows packets in a best-effort class to be processed in the context of a task sending higher priority traffic. If there are packets left in the qdisc after that first run, the NET_TX softirq is raised and gets executed immediately in the same process context. As with any other softirq, it runs up to 10 times and for up to 2ms, during which the calling process is waiting for the sendmsg call (or similar) to return. In my use case, that calling process is a real-time task scheduled to send a packet every 2ms, so the long sendmsg calls are leading to missed timeslots. By attaching each netdev queue to its own qdisc, as it is done with the "classic" mq qdisc, each traffic class can be processed independently without touching the other classes. A high-priority process can then send packets without getting stuck in the sendmsg call anymore. Signed-off-by: Yannick Vignon <yannick.vignon@nxp.com> Signed-off-by: David S. Miller <davem@davemloft.net> |
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| Documentation | ||
| LICENSES | ||
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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.