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Alexander Lobakin 4a36d0180c net: skbuff: always try to recycle PP pages directly when in softirq
Commit 8c48eea3ad ("page_pool: allow caching from safely localized
NAPI") allowed direct recycling of skb pages to their PP for some cases,
but unfortunately missed a couple of other majors.
For example, %XDP_DROP in skb mode. The netstack just calls kfree_skb(),
which unconditionally passes `false` as @napi_safe. Thus, all pages go
through ptr_ring and locks, although most of time we're actually inside
the NAPI polling this PP is linked with, so that it would be perfectly
safe to recycle pages directly.
Let's address such. If @napi_safe is true, we're fine, don't change
anything for this path. But if it's false, check whether we are in the
softirq context. It will most likely be so and then if ->list_owner
is our current CPU, we're good to use direct recycling, even though
@napi_safe is false -- concurrent access is excluded. in_softirq()
protection is needed mostly due to we can hit this place in the
process context (not the hardirq though).
For the mentioned xdp-drop-skb-mode case, the improvement I got is
3-4% in Mpps. As for page_pool stats, recycle_ring is now 0 and
alloc_slow counter doesn't change most of time, which means the
MM layer is not even called to allocate any new pages.

Suggested-by: Jakub Kicinski <kuba@kernel.org> # in_softirq()
Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Reviewed-by: Alexander Duyck <alexanderduyck@fb.com>
Link: https://lore.kernel.org/r/20230804180529.2483231-7-aleksander.lobakin@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-08-07 13:05:53 -07:00
arch Revert "riscv: dts: allwinner: d1: Add CAN controller nodes" 2023-08-07 09:37:31 +02:00
block block-6.5-2023-07-21 2023-07-22 11:05:15 -07:00
certs KEYS: Add missing function documentation 2023-04-24 16:15:52 +03:00
crypto crypto: algif_hash - Fix race between MORE and non-MORE sends 2023-07-08 22:48:42 +10:00
Documentation page_pool: split types and declarations from page_pool.h 2023-08-07 13:05:19 -07:00
drivers page_pool: split types and declarations from page_pool.h 2023-08-07 13:05:19 -07:00
fs nfsd-6.5 fixes: 2023-08-03 09:26:34 -07:00
include page_pool: add a lockdep check for recycling in hardirq 2023-08-07 13:05:53 -07:00
init Kbuild updates for v6.5 2023-07-01 09:24:31 -07:00
io_uring io_uring-6.5-2023-07-28 2023-07-28 10:19:44 -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 pull-request: bpf-next 2023-08-03 2023-08-03 15:34:36 -07:00
lib Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2023-08-03 14:34:37 -07:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm 11 hotfixes. Five are cc:stable and the remainder address post-6.4 issues 2023-07-28 17:19:52 -07:00
net net: skbuff: always try to recycle PP pages directly when in softirq 2023-08-07 13:05:53 -07:00
rust rust: error: impl Debug for Error with errname() integration 2023-06-13 01:24:42 +02:00
samples samples/bpf: README: Update build dependencies required 2023-07-18 17:29:43 -07:00
scripts x86: 2023-07-30 11:19:08 -07:00
security Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2023-08-03 14:34:37 -07:00
sound ASoC: Fixes for v6.5 2023-07-27 14:54:23 +02:00
tools netlink: specs: devlink: add info-get dump op 2023-08-04 14:03:01 -07:00
usr initramfs: Encode dependency on KBUILD_BUILD_TIMESTAMP 2023-06-06 17:54:49 +09:00
virt KVM: Grab a reference to KVM for VM and vCPU stats file descriptors 2023-07-29 11:05:28 -04:00
.clang-format iommu: Add for_each_group_device() 2023-05-23 08:15:51 +02:00
.cocciconfig
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore Revert ".gitignore: ignore *.cover and *.mbx" 2023-07-04 15:05:12 -07:00
.mailmap mailmap: update remaining active codeaurora.org email addresses 2023-07-27 13:07:05 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS - Address -Wmissing-prototype warnings 2023-06-26 16:43:54 -07:00
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 page_pool: split types and declarations from page_pool.h 2023-08-07 13:05:19 -07:00
Makefile Linux 6.5-rc4 2023-07-30 13:23:47 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.