Comment by jorvi

> vm.swappiness defaults to 60, which is default from when everyone was still running spinning rust with a swap partition. Servers these days usually have very specific storage+memory configurations, whereas the usual desktop or laptop has an SSD and 16GB+ of RAM with RAM compression expanding it.

You don't need to compile a specific kernel for that, this is setup via sysctl.

> Lazy RCU loading is good on a laptop

Do you mean RCU_LAZY? Most distros will already enable that: it doesn't do anything without rcu_nocbs, so there's no negative impact on server workloads.

    [calvin@debian-trixie ~] grep RCU_LAZY /boot/config-6.12.57+deb13-amd64
    CONFIG_RCU_LAZY=y
    # CONFIG_RCU_LAZY_DEFAULT_OFF is not set
    [calvin@debian-trixie ~] grep RCU_NOCB_CPU /boot/config-6.12.57+deb13-amd64 
    CONFIG_RCU_NOCB_CPU=y
    # CONFIG_RCU_NOCB_CPU_DEFAULT_ALL is not set

You just have to set rcu_nocbs on the kernel cmdline.

Swappiness and many others can be changed by some sort of system preset rather built that way. I know not ALL options can be done that way, but I'd want to see changes start there where feasible.

I totally missed that part of your comment, my bad. Thanks for elaborating on those, I feel inspired to experiment!

So far my kernel journey has been about making my hardware work + enabling features, and that’s mostly how I’ve been discovering config options. Do you have any suggestions on where one aught to read further on this sort of kernel tuning?

EDIT: doing some further research, couldn’t you just set those options via sysctl w/o needing to build a separate kernel?