linuxdcpp-team team mailing list archive

[maksis <1909853@xxxxxxxxxxxxxxxxxx>]

Public bug reported:

Modern operating systems (Linux 2.4+, Windows Vista+) should support TCP
tuning (https://en.wikipedia.org/wiki/TCP_tuning) to enable higher per-
thread speeds with fast connections. However, the current default socket
buffer size (65536 bytes) set by the client will prevent the feature
from being utilized.

Example: with a 80 ms RTT the maximum transfer speed is about 6.5 Mbps
with the current default buffer values
(https://www.switch.ch/network/tools/tcp_throughput/)

I've done some testing and auto tuning seems to be working as expected.
When downloading from another user (Windows -> Linux) with a 20 ms RTT
and buffer sizes set to 0 in both clients, I was able to utilize my 100
Mbps connection with a single thread, while using the old buffer size
limited the speed to ~30 Mbps, which matches the maximum speed given by
the calculator.

The required code changes are quite trivial: https://github.com/airdcpp
/airdcpp-windows/commit/f96ef123c8152860bb796208cadbe051cc5a8da8

** Affects: dcplusplus
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1909853

Title:
  Don't use custom socket buffer sizes by default

Status in DC++:
  New

Bug description:
  Modern operating systems (Linux 2.4+, Windows Vista+) should support
  TCP tuning (https://en.wikipedia.org/wiki/TCP_tuning) to enable higher
  per-thread speeds with fast connections. However, the current default
  socket buffer size (65536 bytes) set by the client will prevent the
  feature from being utilized.

  Example: with a 80 ms RTT the maximum transfer speed is about 6.5 Mbps
  with the current default buffer values
  (https://www.switch.ch/network/tools/tcp_throughput/)

  I've done some testing and auto tuning seems to be working as
  expected. When downloading from another user (Windows -> Linux) with a
  20 ms RTT and buffer sizes set to 0 in both clients, I was able to
  utilize my 100 Mbps connection with a single thread, while using the
  old buffer size limited the speed to ~30 Mbps, which matches the
  maximum speed given by the calculator.

  The required code changes are quite trivial:
  https://github.com/airdcpp/airdcpp-
  windows/commit/f96ef123c8152860bb796208cadbe051cc5a8da8

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