KVM Optimisations
transmit queue
virsh domiflist
# this is then the txqueuelen change below ???
# changing to 4096
ifconfig txqueuelen
txqueuelen (iwbcman comment)
defaults to 1000, apparently 200 is good
ip link set eth0 txqueuelen 200
vim /etc/network/interfaces
add
post-up /sbin/ip link set eth0 txqueuelen 200
to the end
If virtual hdd is slow can try
Cache mode: none (not default!)
I/O mode: native
https://unix.stackexchange.com/a/48584
non caching on dirves?
https://blog.jdpfu.com/2012/07/30/improving-kvm-performance
://documentation.suse.com/smart/linux/html/concept-virtual-disk-cache-modes/concept-virtual-disk-cache-modes.html#:~:text=A%20disk%20cache%20is%20a,example%2C%20by%20setting%20its%20type.
On VM turning cache off essentially acts like accessing the drive itself. No exactly a passthrough, but decent enough
http://www.linux-kvm.org/page/Tuning_KVM