Can someone please tell me the purpose of limiting the memory available to the kernel?

I have a LINODE 360 with apache2, php5, mysql5 and will be running 5 or 6 database driven websites. MP3's will be streaming randomly on each website though a flash based MP3 player.

What will limiting the kernel memory to 300mb instead of 360mb do? How about 256 instead of 360? 192, 128, 64?

That setting limits the total memory available to the system. Reducing it is like downgrading your Linode. It's handy if you want to test a system's performance under limited resources (developers like to do that sometimes). For a normal user, just leave it set to the max.

--James