Performance tuning

Use the noop IO elevator

$ dd bs=1M count=512 if=/dev/zero of=test conv=fdatasync
536870912 bytes (537 MB) copied, 12,538 s, 42,8 MB/s

$ vim     /etc/default/grub       (GRUB_CMDLINE_LINUX_DEFAULT="elevator=noop")
$ update-grub
$ reboot

$ dd bs=1M count=512 if=/dev/zero of=test conv=fdatasync
536870912 bytes (537 MB) copied, 8,49777 s, 61,8 MB/s

Use para-virtualized block and net devices

$ kvm -drive file=$IMAGE,if=virtio,cache=none -net nic,model=virtio,macaddr=$MAC -net tap,ifname=$NET_DEV,script=no

Expose all host cpu flags to guest OS

$ kvm -cpu host

Assign multiple processors/cores/threads to the guest

$ kvm -smp cores=2,threads=2