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Jakub Kicinski ef04d290c0 net: page_pool: do not count normal frag allocation in stats 
Commit 0f6deac3a0 ("net: page_pool: add page allocation stats for
two fast page allocate path") added increments for "fast path"
allocation to page frag alloc. It mentions performance degradation
analysis but the details are unclear. Could be that the author
was simply surprised by the alloc stats not matching packet count.

In my experience the key metric for page pool is the recycling rate.
Page return stats, however, count returned _pages_ not frags.
This makes it impossible to calculate recycling rate for drivers
using the frag API. Here is example output of the page-pool
YNL sample for a driver allocating 1200B frags (4k pages)
with nearly perfect recycling:

  $ ./page-pool
    eth0[2]	page pools: 32 (zombies: 0)
		refs: 291648 bytes: 1194590208 (refs: 0 bytes: 0)
		recycling: 33.3% (alloc: 4557:2256365862 recycle: 200476245:551541893)

The recycling rate is reported as 33.3% because we give out
4096 // 1200 = 3 frags for every recycled page.

Effectively revert the aforementioned commit. This also aligns
with the stats we would see for drivers which do the fragmentation
themselves, although that's not a strong reason in itself.

On the (very unlikely) path where we can reuse the current page
let's bump the "cached" stat. The fact that we don't put the page
in the cache is just an optimization.

Acked-by: Jesper Dangaard Brouer <hawk@kernel.org>
Reviewed-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Link: https://patch.msgid.link/20241109023303.3366500-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-11-12 18:26:58 -08:00
arch xtensa: remove the get_order() implementation 2024-11-11 10:56:27 -08:00
block block-6.12-20241101 2024-11-01 13:41:55 -10:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto This push fixes the following issues: 2024-10-16 08:42:54 -07:00
Documentation net: Implement fault injection forcing skb reallocation 2024-11-12 12:05:33 +01:00
drivers eth: bnxt: use page pool for head frags 2024-11-12 18:26:38 -08:00
fs eventpoll: Control irq suspension for prefer_busy_poll 2024-11-11 18:45:06 -08:00
include net: Implement fault injection forcing skb reallocation 2024-11-12 12:05:33 +01:00
init cfi: fix conditions for HAVE_CFI_ICALL_NORMALIZE_INTEGERS 2024-10-13 22:23:13 +02:00
io_uring io_uring/rw: fix missing NOWAIT check for O_DIRECT start write 2024-10-31 08:21:02 -06:00
ipc struct fd layout change (and conversion to accessor helpers) 2024-09-23 09:35:36 -07:00
kernel Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2024-11-07 13:44:16 -08:00
lib net: Implement fault injection forcing skb reallocation 2024-11-12 12:05:33 +01:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm mm: page_frag: use __alloc_pages() to replace alloc_pages_node() 2024-11-11 10:56:27 -08:00
net net: page_pool: do not count normal frag allocation in stats 2024-11-12 18:26:58 -08:00
rust Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2024-10-21 09:14:18 +02:00
samples [tree-wide] finally take no_llseek out 2024-09-27 08:18:43 -07:00
scripts Kbuild fixes for v6.12 (2nd) 2024-11-03 08:29:02 -10:00
security KEYS: trusted: dcp: fix NULL dereference in AEAD crypto operation 2024-11-04 21:24:24 +02:00
sound ALSA: hda/realtek: Fix headset mic on TUXEDO Stellaris 16 Gen6 mb1 2024-10-30 14:46:59 +01:00
tools net: ipv4: Cache pmtu for all packet paths if multipath enabled 2024-11-11 19:07:36 -08:00
usr initramfs: shorten cmd_initfs in usr/Makefile 2024-07-16 01:07:52 +09:00
virt ARM64: 2024-10-21 11:22:04 -07:00
.clang-format clang-format: Update with v6.11-rc1's for_each macro list 2024-08-02 13:20:31 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore Add Jeff Kirsher to .get_maintainer.ignore 2024-03-08 11:36:54 +00:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore Kbuild updates for v6.12 2024-09-24 13:02:06 -07:00
.mailmap .mailmap: update e-mail address for Eugen Hristev 2024-10-31 20:27:04 -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 MAINTAINERS: Remove self from DSA entry 2024-11-03 12:52:38 -08:00
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 2024-11-07 13:44:16 -08:00
Makefile Linux 6.12-rc6 2024-11-03 14:05:52 -10:00
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.