Interestingly cache=none doesn't make much odds to the load. I'm not sure what the Debian disk clear is doing to it - see later;
So the combo's I've just tried are: Performance options 'Cache mode: 'default' IO mode 'default' /usr/bin/kvm -name debian -S -M pc-0.12 -cpu Nehalem,+rdtscp,+xtpr,+tm2,+est,+vmx,+ds_cpl,+monitor,+pbe,+tm,+ht,+ss,+acpi,+ds,+vme -enable-kvm -m 2048 -smp 2,sockets=2,cores=1,threads=1 -uuid 27c24103-2985-d338-158e-0aa151ed4f61 -no-user-config -nodefaults -chardev socket,id=charmonitor,path=/var/lib/libvirt/qemu/debian.monitor,server,nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc -no-shutdown -boot order=cd,menu=on -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -drive file=/dev/main/debianvm,if=none,id=drive-virtio-disk0,format=raw -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x5,drive=drive-virtio-disk0,id=virtio-disk0 -drive file=/media/more/isos/debian-wheezy-DI-b1-amd64-netinst-2012-08-12.iso,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 -netdev tap,fd=21,id=hostnet0,vhost=on,vhostfd=22 -device virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:6f:c0:33,bus=pci.0,addr=0x3 -chardev pty,id=charserial0 -device isa-serial,chardev=charserial0,id=serial0 -device usb-tablet,id=input0 -vnc 127.0.0.1:0 -vga cirrus -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x6 Load average 10+, ~6MB/s ---- Performance options 'Cache mode: 'None' IO mode 'default' /usr/bin/kvm -name debian -S -M pc-0.12 -cpu Nehalem,+rdtscp,+xtpr,+tm2,+est,+vmx,+ds_cpl,+monitor,+pbe,+tm,+ht,+ss,+acpi,+ds,+vme -enable-kvm -m 2048 -smp 2,sockets=2,cores=1,threads=1 -uuid 27c24103-2985-d338-158e-0aa151ed4f61 -no-user-config -nodefaults -chardev socket,id=charmonitor,path=/var/lib/libvirt/qemu/debian.monitor,server,nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc -no-shutdown -boot order=cd,menu=on -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -drive file=/dev/main/debianvm,if=none,id=drive-virtio-disk0,format=raw,cache=none -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x5,drive=drive-virtio-disk0,id=virtio-disk0 -drive file=/media/more/isos/debian-wheezy-DI-b1-amd64-netinst-2012-08-12.iso,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 -netdev tap,fd=21,id=hostnet0,vhost=on,vhostfd=22 -device virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:6f:c0:33,bus=pci.0,addr=0x3 -chardev pty,id=charserial0 -device isa-serial,chardev=charserial0,id=serial0 -device usb-tablet,id=input0 -vnc 127.0.0.1:0 -vga cirrus -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x6 Load average ~7, 6MB/s during the erase disk operation --- Performance options 'Cache mode: 'None' Io mode 'native' usr/bin/kvm -name debian -S -M pc-0.12 -cpu Nehalem,+rdtscp,+xtpr,+tm2,+est,+vmx,+ds_cpl,+monitor,+pbe,+tm,+ht,+ss,+acpi,+ds,+vme -enable-kvm -m 2048 -smp 2,sockets=2,cores=1,threads=1 -uuid 27c24103-2985-d338-158e-0aa151ed4f61 -no-user-config -nodefaults -chardev socket,id=charmonitor,path=/var/lib/libvirt/qemu/debian.monitor,server,nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc -no- shutdown -boot order=cd,menu=on -device piix3-usb- uhci,id=usb,bus=pci.0,addr=0x1.0x2 -drive file=/dev/main/debianvm,if=none,id=drive-virtio- disk0,format=raw,cache=none,aio=native -device virtio-blk- pci,scsi=off,bus=pci.0,addr=0x5,drive=drive-virtio-disk0,id=virtio-disk0 -drive file=/media/more/isos/debian-wheezy- DI-b1-amd64-netinst-2012-08-12.iso,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 -netdev tap,fd=21,id=hostnet0,vhost=on,vhostfd=22 -device virtio-net- pci,netdev=hostnet0,id=net0,mac=52:54:00:6f:c0:33,bus=pci.0,addr=0x3 -chardev pty,id=charserial0 -device isa- serial,chardev=charserial0,id=serial0 -device usb-tablet,id=input0 -vnc 127.0.0.1:0 -vga cirrus -device virtio-balloon- pci,id=balloon0,bus=pci.0,addr=0x6 Load average of ~1 - but still only 6MB/s! So I tried a couple more tests; on the host I did: dd if=/dev/zero of=/dev/main/debianvm bs=65536 conv=fsync on the host gives 111MB/s 21474836480 bytes (21 GB) copied, 194.302 s, 111 MB/s so that's happy on the host. Doing a ps during debian's disk wipe I see it's doing a : /bin/blockdev-wipe -s 65536 /dev/mapper/crypt0 but if I try on the guest a dd if=/dev/zero of=/dev/vda5 bs=64k it gives >100MB/s even dd'ing into the encrypted /dev/mapper/debian-root in the guest is getting >70MB/s - and a host load average of over 50! So whatever is going on, the speed seems to be related to blockdev-wipe, and not qemu. The loadaverage however is qemus threaded IO mode; I guess that's an artifact rather than a real problem. The host isn't feeling slow - it's just the artifically high load average. There is a bug 945001 that's about blockdev-wipe being slow; not obvious what he ran that on; but the code for blockdev-wipe doesn't seem unusual; it's just a loop doing a write() and frobbing around with progress indicators. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1035921 Title: odd IO/load behaviour running debian installer guest To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/qemu-kvm/+bug/1035921/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
