performance – RockyOS/CentOS/RedHat OS – VMWare to OpenStack migration – server too slow (e.g. up to 3x)

Instructions on how to speed up a server that is too slow after migrating from VMWare to OpenStack.

1. Disable tuned service.

2. Changing kernel settings.
   grubby --update-kernel ALL --args "selinux=0 idle=poll intel_idle.max_cstate=0 intel_pstate=disable processor.max_cstate=1 elevator=none"

3. Reboot server

4. Changing read-ahead settings – new systemd file.

   i) file:
   /etc/systemd/system/setra.service

   ii) content (for devices /dev/vda, dev/dm-[0,2]):
   — START —
   [Unit]
Description=Set custom read-ahead for devices
After=tuned.service
[Service]
Type=oneshot
ExecStart=/sbin/blockdev --setra 32768 /dev/vda
ExecStart=/sbin/blockdev --setra 32768 /dev/dm-0
ExecStart=/sbin/blockdev --setra 32768 /dev/dm-1
ExecStart=/sbin/blockdev --setra 32768 /dev/dm-2
[Install]
WantedBy=multi-user.target
   — STOP —

   iii) activation:
   systemctl enable setra.service
systemctl start setra.service

5. Changing read-ahead settings – new udev file.
   i) file:
   /etc/udev/rules.d/999-ssd.rules

   ii) content (for devices /dev/vda, dev/dm-[0,2]):
   — START —
   SUBSYSTEM=="block", ACTION=="add|change", KERNEL=="vda", ATTR{queue/read_ahead_kb}="32768", ATTR{queue/rotational}="0"
SUBSYSTEM=="block", ACTION=="add|change", KERNEL=="dm-[0-2]", ATTR{queue/read_ahead_kb}="32768", ATTR{queue/rotational}="0"

   — STOP —

6. Reboot server.