Hi, I found an obvious performance downgrade when virtio-console combined with virtio-pci-blk. This phenomenon exists in nearly all Qemu versions and all Linux (CentOS7, Fedora 28, Ubuntu 18.04) distros. This is a disk cmd: -drive file=iscsi://127.0.0.1:3260/iqn.2016-02.com.test:system:fl-iscsi/1,format=raw,if=none,id=drive-virtio-disk0,cache=none,aio=native -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x6,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1,write-cache=on If I add "-device virtio-serial-pci,id=virtio-serial0,bus=pci.0,addr=0x5 ", the virtio disk 4k iops (randread/randwrite) would downgrade from 60k to 40k. In VM, if I rmmod virtio-console, the performance will back to normal. Any idea about this issue? I don't know this is a qemu issue or kernel issue. Thanks in advance. -- Thanks and Best Regards, Alex
