mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-05-10 05:39:42 -04:00
c0b0a360ed
Jesper Dangaard Brouer says: ==================== veth: qdisc backpressure and qdisc check refactor This patch series addresses TX drops seen on veth devices under load, particularly when using threaded NAPI, which is our setup in production. The root cause is that the NAPI consumer often runs on a different CPU than the producer. Combined with scheduling delays or simply slower consumption, this increases the chance that the ptr_ring fills up before packets are drained, resulting in drops from veth_xmit() (ndo_start_xmit()). To make this easier to reproduce, we’ve created a script that sets up a test scenario using network namespaces. The script inserts 1000 iptables rules in the consumer namespace to slow down packet processing and amplify the issue. Reproducer script: https://github.com/xdp-project/xdp-project/blob/main/areas/core/veth_setup01_NAPI_TX_drops.sh This series first introduces a helper to detect no-queue qdiscs and then uses it in the veth driver to conditionally apply qdisc-level backpressure when a real qdisc is attached. The behavior is off by default and opt-in, ensuring minimal impact and easy activation. v6: https://lore.kernel.org/174549933665.608169.392044991754158047.stgit@firesoul v5: https://lore.kernel.org/174489803410.355490.13216831426556849084.stgit@firesoul v4 https://lore.kernel.org/174472463778.274639.12670590457453196991.stgit@firesoul v3: https://lore.kernel.org/174464549885.20396.6987653753122223942.stgit@firesoul v2: https://lore.kernel.org/174412623473.3702169.4235683143719614624.stgit@firesoul RFC-v1: https://lore.kernel.org/174377814192.3376479.16481605648460889310.stgit@firesoul ==================== Link: https://patch.msgid.link/174559288731.827981.8748257839971869213.stgit@firesoul Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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.