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Toke Høiland-Jørgensen 4876376988 Revert "mac80211: Dynamically set CoDel parameters per station" 
This reverts commit 484a54c2e5. The CoDel
parameter change essentially disables CoDel on slow stations, with some
questionable assumptions, as Dave pointed out in [0]. Quoting from
there:

  But here are my pithy comments as to why this part of mac80211 is so
  wrong...

   static void sta_update_codel_params(struct sta_info *sta, u32 thr)
   {
  -       if (thr && thr < STA_SLOW_THRESHOLD * sta->local->num_sta) {

  1) sta->local->num_sta is the number of associated, rather than
  active, stations. "Active" stations in the last 50ms or so, might have
  been a better thing to use, but as most people have far more than that
  associated, we end up with really lousy codel parameters, all the
  time. Mistake numero uno!

  2) The STA_SLOW_THRESHOLD was completely arbitrary in 2016.

  -               sta->cparams.target = MS2TIME(50);

  This, by itself, was probably not too bad. 30ms might have been
  better, at the time, when we were battling powersave etc, but 20ms was
  enough, really, to cover most scenarios, even where we had low rate
  2Ghz multicast to cope with. Even then, codel has a hard time finding
  any sane drop rate at all, with a target this high.

  -               sta->cparams.interval = MS2TIME(300);

  But this was horrible, a total mistake, that is leading to codel being
  completely ineffective in almost any scenario on clients or APS.
  100ms, even 80ms, here, would be vastly better than this insanity. I'm
  seeing 5+seconds of delay accumulated in a bunch of otherwise happily
  fq-ing APs....

  100ms of observed jitter during a flow is enough. Certainly (in 2016)
  there were interactions with powersave that I did not understand, and
  still don't, but if you are transmitting in the first place, powersave
  shouldn't be a problemmmm.....

  -               sta->cparams.ecn = false;

  At the time we were pretty nervous about ecn, I'm kind of sanguine
  about it now, and reliably indicating ecn seems better than turning it
  off for any reason.

  [...]

  In production, on p2p wireless, I've had 8ms and 80ms for target and
  interval for years now, and it works great.

I think Dave's arguments above are basically sound on the face of it,
and various experimentation with tighter CoDel parameters in the OpenWrt
community have show promising results[1]. So I don't think there's any
reason to keep this parameter fiddling; hence this revert.

[0] https://lore.kernel.org/linux-wireless/CAA93jw6NJ2cmLmMauz0xAgC2MGbBq6n0ZiZzAdkK0u4b+O2yXg@mail.gmail.com/
[1] https://forum.openwrt.org/t/reducing-multiplexing-latencies-still-further-in-wifi/133605/130

Suggested-By: Dave Taht <dave.taht@gmail.com>
In-memory-of: Dave Taht <dave.taht@gmail.com>
Signed-off-by: Toke Høiland-Jørgensen <toke@toke.dk>
Link: https://patch.msgid.link/20250403183930.197716-1-toke@toke.dk
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2025-04-23 15:22:11 +02:00
arch xen: branch for v6.15-rc3 2025-04-17 10:24:22 -07:00
block treewide: Switch/rename to timer_delete[_sync]() 2025-04-05 10:30:12 +02:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto crypto: ahash - Disable request chaining 2025-04-12 09:33:09 +08:00
Documentation dt-bindings: wireless: qcom,wcnss: Use wireless-controller.yaml 2025-04-23 15:20:01 +02:00
drivers wifi: iwlwifi: mvm: Avoid -Wflex-array-member-not-at-end warning 2025-04-23 15:20:58 +02:00
fs XFS fixes for 6.15-rc3 2025-04-17 09:24:56 -07:00
include Revert "mac80211: Dynamically set CoDel parameters per station" 2025-04-23 15:22:11 +02:00
init Miscellaneous scheduler fixes/updates: 2025-04-06 10:44:58 -07:00
io_uring io_uring/kbuf: reject zero sized provided buffers 2025-04-07 07:51:23 -06:00
ipc treewide: const qualify ctl_tables where applicable 2025-01-28 13:48:37 +01:00
kernel tracing fixes for v6.15 2025-04-12 15:37:40 -07:00
lib 31 hotfixes. 9 are cc:stable and the remainder address post-6.15 issues 2025-04-16 20:07:32 -07:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm slab fix for 6.15-rc2 2025-04-17 09:11:33 -07:00
net Revert "mac80211: Dynamically set CoDel parameters per station" 2025-04-23 15:22:11 +02:00
rust Kbuild updates for v6.15 2025-04-05 15:46:50 -07:00
samples samples/livepatch: add module descriptions 2025-04-11 17:32:38 -07:00
scripts Disable SLUB_TINY for build testing 2025-04-06 10:00:04 -07:00
security mseal sysmap: kernel config and header change 2025-04-01 15:17:14 -07:00
sound ASoC: Fixes for v6.15 2025-04-11 15:51:19 +02:00
tools Including fixes from Bluetooth, CAN and Netfilter. 2025-04-17 11:45:30 -07:00
usr kbuild: hdrcheck: fix cross build with clang 2025-03-05 04:06:45 +09:00
virt ARM: 2025-04-08 13:47:55 -07:00
.clang-format clang-format: Update with v6.11-rc1's for_each macro list 2024-08-02 13:20:31 +02:00
.clippy.toml rust: give Clippy the minimum supported Rust version 2025-01-10 00:17:25 +01:00
.cocciconfig
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore MAINTAINERS: Retire Ralf Baechle 2024-11-12 15:48:59 +01:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: Create intermediate vmlinux build with relocations preserved 2025-03-17 00:29:50 +09:00
.mailmap sound fixes for 6.15-rc3 2025-04-17 10:14:51 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING
CREDITS Including fixes from netfilter. 2025-04-04 09:15:35 -07:00
Kbuild drm: ensure drm headers are self-contained and pass kernel-doc 2025-02-12 10:44:43 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS Including fixes from Bluetooth, CAN and Netfilter. 2025-04-17 11:45:30 -07:00
Makefile Linux 6.15-rc2 2025-04-13 11:54:49 -07:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

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 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.