Stripping down a kernel in linux?

Question

I recently read a post (admittedly its a few years old) and it was advice for fast number-crunching program:

"Use something like Gentoo Linux with 64 bit processors as you can compile it natively as you install. This will allow you to get the maximum punch out of the machine as you can strip the kernel right down to only what you need."

can anyone elaborate on what they mean by stripping down the kernel? Also, as this post was about 6 years old, which current version of Linux would be best for this (to aid my google searches)?

Answer 1

There is some truth in the statement, as well as something somewhat nonsensical.

You do not spend resources on processes you are not running. So as a first instance I would try minimise the number of processes running. For that we quite enjoy Ubuntu server iso images at work -- if you install from those, log in and run ps or pstree you see a thing of beauty: six or seven processes. Nothing more. That is good.

That the kernel is big (in terms of source size or installation) does not matter per se. Many of this size stems from drivers you may not be using anyway. And the same rule applies again: what you do not run does not compete for resources.

So think about a headless server, stripped down -- rather than your average desktop installation with more than a screenful of processes trying to make the life of a desktop user easier.

Answer 2

You can create a custom linux kernel for any distribution.

Start by going to kernel.org and downloading the latest source. Then choose your configuration interface (you have the choice of console text, 'config', ncurses style 'menuconfig', KDE style 'xconfig' and GNOME style 'gconfig' these days) and execute ./make whateverconfig. After choosing all the options, type make to create your kernel. Then make modules to compile all the selected modules for this kernel. Then, make install will copy the files to your /boot directory, and make modules_install, copies the modules. Next, go to /boot and use mkinitrd to create the ram disk needed to boot properly, if needed. Then you'll add the kernel to your GRUB menu.lst, by editing menu.lst and copying the latest entry and adding a similar one pointing to the new kernel version.

Of course, that's a basic overview and you should probably search for 'linux kernel compile' to find more detailed info. Selecting the necessary kernel modules and options takes a bit of experience - if you choose the wrong options, the kernel might not be bootable and you'll have to start over, which is a pain because selecting the options and compiling the kernel can take 15-30 minutes.

Ultimately, it isn't going to make a large difference to compile a stripped-down custom kernel unless your given task is very, very performance sensitive. It makes sense to remove things you're never going to use from the kernel, though, like say ISDN support.

I'd have to say this question is more suited to SuperUser.com, by the way, as it's not quite about programming.