I am running dpdk with a virtual guest as a L2 forwarder. If the virtual guest is on passthrough, dpdk can achieve around 10G throughput. However if the virtual guest is on virtio, dpdk achieves just 150M throughput, which is a huge degrade. Any idea what could be the cause of such poor performance on virtio? and any performance tuning techniques I could try? Thanks a lot!
lab at vpc-2:~$ ps aux | grep qemu libvirt+ 12020 228 0.0 102832508 52860 ? Sl 14:54 61:06 *qemu*-system-x86_64 -enable-kvm -name dpdk-perftest -S -machine pc-i440fx-trusty,accel=kvm,usb=off,mem-merge=off -cpu host -m 98304 -mem-prealloc -mem-path /dev/hugepages/libvirt/*qemu* -realtime mlock=off -smp 24,sockets=2,cores=12,threads=1 -numa node,nodeid=0,cpus=0-11,mem=49152 -numa node,nodeid=1,cpus=12-23,mem=49152 -uuid eb5f8848-9983-4f13-983c-e3bd4c59387d -no-user-config -nodefaults -chardev socket,id=charmonitor,path=/var/lib/libvirt/*qemu*/dpdk-perftest.monitor,server,nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc -no-shutdown -boot strict=on -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -drive file=/var/lib/libvirt/images/dpdk-perftest-hda.img,if=none,id=drive-ide0-0-0,format=qcow2 -device ide-hd,bus=ide.0,unit=0,drive=drive-ide0-0-0,id=ide0-0-0,bootindex=1 -drive file=/var/lib/libvirt/images/dpdk-perftest-hdb.img,if=none,id=drive-ide0-0-1,format=qcow2 -device ide-hd,bus=ide.0,unit=1,drive=drive-ide0-0-1,id=ide0-0-1 -drive if=none,id=drive-ide0-1-0,readonly=on,format=raw -device ide-cd,bus=ide.1,unit=0,drive=drive-ide0-1-0,id=ide0-1-0,bootindex=2 -netdev tap,fd=24,id=hostnet0,vhost=on,vhostfd=25 -device virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:45:ff:5e,bus=pci.0,addr=0x5 -netdev tap,fds=26:27:28:29:30:31:32:33,id=hostnet1,vhost=on,vhostfds=34:35:36:37:38:39:40:41 -device virtio-net-pci,mq=on,vectors=17,netdev=hostnet1,id=net1,mac=52:54:00:7e:b5:6b,bus=pci.0,addr=0x6 -netdev tap,fds=42:43:44:45:46:47:48:49,id=hostnet2,vhost=on,vhostfds=50:51:52:53:54:55:56:57 -device virtio-net-pci,mq=on,vectors=17,netdev=hostnet2,id=net2,mac=52:54:00:f1:a5:20,bus=pci.0,addr=0x7 -chardev pty,id=charserial0 -device isa-serial,chardev=charserial0,id=serial0 -chardev pty,id=charserial1 -device isa-serial,chardev=charserial1,id=serial1 -vnc 127.0.0.1:0 -device cirrus-vga,id=video0,bus=pci.0,addr=0x2 -device i6300esb,id=watchdog0,bus=pci.0,addr=0x3 -watchdog-action reset -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x4
