On Mon, Dec 06, 2021 at 02:28:35PM +0000, Phil Endecott wrote: > On one of my Lightsail instances, which was created a few years > ago from a Debian image and has subsequently been upgraded a few > times, I have a /etc/sysctl.d/01_ec2.conf file which sets > vm.swappiness = 0. On another newer EC2 instance I don't have this > file.
Right; we haven't shipped that file since (IIRC) jessie. > dpkg -S doesn't tell me where this file came from. I don't > think I created it myself!! It was installed as part of the image creation process. Similar to files like /etc/hosts, it is not actually owned by a package. > Does anyone recognise this? Of course the issue is that I > discovered the hard way that the system was not using its > swapfile. The file has a pile of other configuration settings > and I wonder if any of those are also undesirable, see below. Most of the settings from that file were lifted from Amazon Linux, IIRC, and are pretty reasonable for a default "server" class VM. Even vm.swappiness is a reasonable default, given that there's no swap file created by default. But nothing will break if you choose to remove the file. noah > vm.swappiness = 0 > vm.dirty_ratio = 80 > vm.dirty_background_ratio = 5 > vm.dirty_expire_centisecs = 12000 > net.core.somaxconn = 1000 > net.core.netdev_max_backlog = 5000 > net.core.rmem_max = 16777216 > net.core.wmem_max = 16777216 > net.ipv4.tcp_wmem = 4096 12582912 16777216 > net.ipv4.tcp_rmem = 4096 12582912 16777216 > net.ipv4.tcp_max_syn_backlog = 8096 > net.ipv4.tcp_slow_start_after_idle = 0 > net.ipv4.tcp_tw_reuse = 1 > net.ipv4.ip_local_port_range = 10240 65535 > kernel.sysrq = 0
