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Jon Maxwell af6d10345c ipv6: remove max_size check inline with ipv4
In ip6_dst_gc() replace:

  if (entries > gc_thresh)

With:

  if (entries > ops->gc_thresh)

Sending Ipv6 packets in a loop via a raw socket triggers an issue where a
route is cloned by ip6_rt_cache_alloc() for each packet sent. This quickly
consumes the Ipv6 max_size threshold which defaults to 4096 resulting in
these warnings:

[1]   99.187805] dst_alloc: 7728 callbacks suppressed
[2] Route cache is full: consider increasing sysctl net.ipv6.route.max_size.
.
.
[300] Route cache is full: consider increasing sysctl net.ipv6.route.max_size.

When this happens the packet is dropped and sendto() gets a network is
unreachable error:

remaining pkt 200557 errno 101
remaining pkt 196462 errno 101
.
.
remaining pkt 126821 errno 101

Implement David Aherns suggestion to remove max_size check seeing that Ipv6
has a GC to manage memory usage. Ipv4 already does not check max_size.

Here are some memory comparisons for Ipv4 vs Ipv6 with the patch:

Test by running 5 instances of a program that sends UDP packets to a raw
socket 5000000 times. Compare Ipv4 and Ipv6 performance with a similar
program.

Ipv4:

Before test:

MemFree:        29427108 kB
Slab:             237612 kB

ip6_dst_cache       1912   2528    256   32    2 : tunables    0    0    0
xfrm_dst_cache         0      0    320   25    2 : tunables    0    0    0
ip_dst_cache        2881   3990    192   42    2 : tunables    0    0    0

During test:

MemFree:        29417608 kB
Slab:             247712 kB

ip6_dst_cache       1912   2528    256   32    2 : tunables    0    0    0
xfrm_dst_cache         0      0    320   25    2 : tunables    0    0    0
ip_dst_cache       44394  44394    192   42    2 : tunables    0    0    0

After test:

MemFree:        29422308 kB
Slab:             238104 kB

ip6_dst_cache       1912   2528    256   32    2 : tunables    0    0    0
xfrm_dst_cache         0      0    320   25    2 : tunables    0    0    0
ip_dst_cache        3048   4116    192   42    2 : tunables    0    0    0

Ipv6 with patch:

Errno 101 errors are not observed anymore with the patch.

Before test:

MemFree:        29422308 kB
Slab:             238104 kB

ip6_dst_cache       1912   2528    256   32    2 : tunables    0    0    0
xfrm_dst_cache         0      0    320   25    2 : tunables    0    0    0
ip_dst_cache        3048   4116    192   42    2 : tunables    0    0    0

During Test:

MemFree:        29431516 kB
Slab:             240940 kB

ip6_dst_cache      11980  12064    256   32    2 : tunables    0    0    0
xfrm_dst_cache         0      0    320   25    2 : tunables    0    0    0
ip_dst_cache        3048   4116    192   42    2 : tunables    0    0    0

After Test:

MemFree:        29441816 kB
Slab:             238132 kB

ip6_dst_cache       1902   2432    256   32    2 : tunables    0    0    0
xfrm_dst_cache         0      0    320   25    2 : tunables    0    0    0
ip_dst_cache        3048   4116    192   42    2 : tunables    0    0    0

Tested-by: Andrea Mayer <andrea.mayer@uniroma2.it>
Signed-off-by: Jon Maxwell <jmaxwell37@gmail.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20230112012532.311021-1-jmaxwell37@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-01-13 20:59:14 -08:00
arch Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2023-01-12 19:59:56 -08:00
block block-2023-01-06 2023-01-06 13:12:42 -08:00
certs certs: make system keyring depend on built-in x509 parser 2022-09-24 04:31:18 +09:00
crypto This update includes the following changes: 2022-12-14 12:31:09 -08:00
Documentation dt-bindings: net: rockchip-dwmac: fix rv1126 compatible warning 2023-01-13 20:15:39 -08:00
drivers net: qualcomm: rmnet: add ethtool support for configuring tx aggregation 2023-01-13 10:23:52 +00:00
fs Including fixes from rxrpc. 2023-01-12 18:20:44 -06:00
include ipv6: remove max_size check inline with ipv4 2023-01-13 20:59:14 -08:00
init gcc: disable -Warray-bounds for gcc-11 too 2023-01-09 17:04:49 -06:00
io_uring io_uring: fix CQ waiting timeout handling 2023-01-05 08:04:47 -07:00
ipc Non-MM patches for 6.2-rc1. 2022-12-12 17:28:58 -08:00
kernel Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2023-01-12 19:59:56 -08:00
lib v6.2 first rc pull request 2023-01-07 10:06:47 -08:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm memblock: Fix doc for memblock_phys_free 2023-01-04 12:31:22 +02:00
net ipv6: remove max_size check inline with ipv4 2023-01-13 20:59:14 -08:00
rust rust: types: add Opaque type 2022-12-04 01:59:16 +01:00
samples bpf-next-for-netdev 2023-01-04 20:21:25 -08:00
scripts kbuild: readd -w option when vmlinux.o or Module.symver is missing 2023-01-05 16:53:48 +09:00
security kernel hardening fixes for v6.2-rc1 2022-12-23 12:00:24 -08:00
sound xen: branch for v6.2-rc4 2023-01-12 17:02:20 -06:00
tools Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2023-01-12 19:59:56 -08:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt Merge branch 'kvm-late-6.1-fixes' into HEAD 2022-12-28 07:19:14 -05:00
.clang-format iommufd for 6.2 2022-12-14 09:15:43 -08:00
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.mailmap MAINTAINERS: Update email of Tudor Ambarus 2023-01-07 15:18:44 +01:00
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CREDITS MAINTAINERS: zram: zsmalloc: Add an additional co-maintainer 2022-12-15 16:37:49 -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 net: dsa: microchip: ptp: add 4 bytes in tail tag when ptp enabled 2023-01-13 08:40:40 +00:00
Makefile Linux 6.2-rc3 2023-01-08 11:49:43 -06:00
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.