336c39a031
Linux implements RFC6298 and use an initial congestion window of 1 upon establishing the connection if the SYNACK packet is retransmitted 2 or more times. In cellular networks SYNACK timeouts are often spurious if the wireless radio was dormant or idle. Also some network path is longer than the default SYNACK timeout. In both cases falsely starting with a minimal cwnd are detrimental to performance. This patch avoids doing so when the final ACK's TCP timestamp indicates the original SYNACK was delivered. It remembers the original SYNACK timestamp when SYNACK timeout has occurred and re-uses the function to detect spurious SYN timeout conveniently. Note that a server may receives multiple SYNs from and immediately retransmits SYNACKs without any SYNACK timeout. This often happens on when the client SYNs have timed out due to wireless delay above. In this case since the server will still use the default initial congestion (e.g. 10) because tp->undo_marker is reset in tcp_init_metrics(). This is an intentional design because packets are not lost but delayed. This patch only covers regular TCP passive open. Fast Open is supported in the next patch. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Eric Dumazet <edumazet@google.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.