Hi,

I ran a fio test to simulate qemu-kvm io behaviour.
When job number is greater than 2, IO performance is
really bad.

1 thread: aggrb=15,129KB/s
4 thread: aggrb=1,049KB/s

Kernel: lastest upstream

Any idea?

---
[global]
runtime=30
time_based=1
size=1G
group_reporting=1
ioengine=posixaio
exec_prerun='echo 3 > /proc/sys/vm/drop_caches'
thread=1

[kvmio-1]
description=kvmio-1
numjobs=4
rw=write
bs=4k
direct=1
filename=/mnt/sda4/1G.img