Sysctl.d settings that need reconsideration

[lunzima]

Bug description

The value of kernel.shmmax can be further expanded and used in conjunction with other settings, such as the following example (reasonable for systems of more than 2Gigs of RAM) :
kernel.shmmni=512
kernel.shmmax=2147483648
kernel.shmall=1048576
kernel.sem=250 256000 100 512
kernel.msgmni=2048
kernel.msgmax=65536
kernel.msgmnb=65536

vm.mmap_min_addr could be increased to 65536 for AMD64/AArch64 and 32768 for 32-bit ARM. For other architectures, keep the default value (4096).
Should vm.dirty_ratio be set to a more conservative value, such as vm.dirty_ratio=10 (default 20)?
Then set vm.dirty_background_ratio to 3 or 5.
You might set
vm.laptop_mode=5
vm.dirty_expire_centisecs=2000
together with vm.dirty_writeback_centisecs=1500.
To save a lot of power, set vm.dirty_expire_centisecs=9000 vm.dirty_writeback_centisecs=6000. This is only recommended if you have a battery/UPS!

For all net.ipv4.conf.all.* and net.ipv6.conf.all.* options, the corresponding net.ipv4.conf.default.* and net.ipv6.conf.default.* options should be set to make the options take effect on all existing and subsequently hot-plugged adapters.
net.ipv4.conf.all.rp_filter=1 may not be friendly to split-tunneling or multi-hosting scenarios. A more conservative option is net.ipv4.conf.all.rp_filter=2.
net.ipv4.conf.all.log_martians=1 may not be that useful to non-network administrator users.

Steps to reproduce

Not relevant

Update channel(s)

stable

Package and version

aosc-aaa 11.5.2
should affect Retro/Afterglow too.

[lunzima]

https://paste.aosc.io/paste/yodQezbgjXJMiueWiUChvw
Some "ancestral" sysctl.conf configuration file