iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity
1,186,340 Commits 104 Branches 1,843 Tags 5.7 GiB
C 97.6%
Assembly 1%
Shell 0.5%
Python 0.3%
Makefile 0.3%
c857946a4e
Go to file
Kurt Kanzenbach c857946a4e net/core: Enable socket busy polling on -RT 
Busy polling is currently not allowed on PREEMPT_RT, because it disables
preemption while invoking the NAPI callback. It is not possible to acquire
sleeping locks with disabled preemption. For details see commit
20ab39d13e ("net/core: disable NET_RX_BUSY_POLL on PREEMPT_RT").

However, strict cyclic and/or low latency network applications may prefer busy
polling e.g., using AF_XDP instead of interrupt driven communication.

The preempt_disable() is used in order to prevent the poll_owner and NAPI owner
to be preempted while owning the resource to ensure progress. Netpoll performs
busy polling in order to acquire the lock. NAPI is locked by setting the
NAPIF_STATE_SCHED flag. There is no busy polling if the flag is set and the
"owner" is preempted. Worst case is that the task owning NAPI gets preempted and
NAPI processing stalls.  This is can be prevented by properly prioritising the
tasks within the system.

Allow RX_BUSY_POLL on PREEMPT_RT if NETPOLL is disabled. Don't disable
preemption on PREEMPT_RT within the busy poll loop.

Tested on x86 hardware with v6.1-RT and v6.3-RT on Intel i225 (igc) with
AF_XDP/ZC sockets configured to run in busy polling mode.

Suggested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
2023-05-26 08:51:26 +01:00
arch Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2023-05-25 20:56:43 -07:00
block block: Deny writable memory mapping if block is read-only 2023-05-19 20:17:10 -06:00
certs KEYS: Add missing function documentation 2023-04-24 16:15:52 +03:00
crypto This push fixes the following problems: 2023-05-07 10:57:14 -07:00
Documentation Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2023-05-25 20:56:43 -07:00
drivers Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2023-05-25 20:56:43 -07:00
fs Changes since last update: 2023-05-23 10:47:32 -07:00
include Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2023-05-25 20:56:43 -07:00
init Objtool changes for v6.4: 2023-04-28 14:02:54 -07:00
io_uring net: Declare MSG_SPLICE_PAGES internal sendmsg() flag 2023-05-23 20:48:27 -07:00
ipc Merge branch 'work.namespace' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2023-02-24 19:20:07 -08:00
kernel Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2023-05-25 20:56:43 -07:00
lib Eight hotfixes. Four are cc:stable, the other four are for post-6.4 2023-05-18 17:06:04 -07:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm: fix zswap writeback race condition 2023-05-17 15:24:33 -07:00
net net/core: Enable socket busy polling on -RT 2023-05-26 08:51:26 +01:00
rust Rust changes for v6.4 2023-04-30 11:20:22 -07:00
samples Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2023-05-25 19:57:39 -07:00
scripts bpf-next-for-netdev 2023-05-16 19:50:05 -07:00
security integrity-v6.4 2023-04-29 10:11:32 -07:00
sound ALSA: hda/realtek: Enable headset onLenovo M70/M90 2023-05-24 14:18:59 +02:00
tools Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2023-05-25 20:56:43 -07:00
usr initramfs: Check negative timestamp to prevent broken cpio archive 2023-04-16 17:37:01 +09:00
virt KVM: Fix vcpu_array[0] races 2023-05-19 13:56:26 -04:00
.clang-format cxl for v6.4 2023-04-30 11:51:51 -07:00
.cocciconfig
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for *.dtso files 2023-02-26 15:28:23 +09:00
.gitignore linux-kselftest-kunit-6.4-rc1 2023-04-24 12:31:32 -07:00
.mailmap mailmap: add entries for Nikolay Aleksandrov 2023-05-17 09:35:05 +01:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING
CREDITS MAINTAINERS: sctp: move Neil to CREDITS 2023-05-12 08:51:32 +01:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2023-05-25 20:56:43 -07:00
Makefile Linux 6.4-rc3 2023-05-21 14:05:48 -07:00
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.