Re: FreeBSD boot hangs on qemu-kvm on AMD host

2011-03-09 Thread Dominik Klein 
 Please try kvm.git and 
 report, it's likely fixed.

With kvm.git kernel it works.

Here's what I did:

git clone git://git.kernel.org/pub/scm/virt/kvm/kvm.git
cd kvm
cp /boot/config-$(uname -r) .config
# set LOCALVERSION to -kvm.git.20110309
make modules bzImage
make modules_install install
# build initrd
reboot
/usr/bin/qemu-kvm -vnc 127.0.0.1:0 -cdrom
/root/isos/FreeBSD-8.2-RELEASE-amd64-disc1.iso
vncviewer localhost:0
# visually verify that it does not hang as it did before

Regards
Dominik
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cgroup limits only affect kvm guest under certain conditions

2011-01-06 Thread Dominik Klein 
Hi

I am playing with cgroups and try to limit block io for guests.

The proof of concept is:

# mkdir /dev/cgroup/blkio
# mount -t cgroup -o blkio blkio /dev/cgroup/blkio/
# cd blkio/
# mkdir test
# cd test/
# ls -l /dev/vdisks/kirk
lrwxrwxrwx 1 root root 7 2011-01-06 13:46 /dev/vdisks/kirk - ../dm-5
# ls -l /dev/dm-5
brw-rw 1 root disk 253, 5 2011-01-06 13:36 /dev/dm-5
# echo 253:5  1048576  blkio.throttle.write_bps_device
# echo $$  tasks
# dd if=/dev/zero of=/dev/dm-5 bs=1M count=20
20+0 records in
20+0 records out
20971520 bytes (21 MB) copied, 20.0223 s, 1.0 MB/s

So limit applies to the dd child of my shell.

Now I assign /dev/dm-5 (/dev/vdisks/kirk) to a vm and echo the qemu-kvm
pid into tasks. Limits are not applied, the guest can happily use max io
bandwidth.

However, if I start the guest manually like

# qemu-kvm options like libvirt creates  echo $! 
/dev/cgroup/blkio/test/tasks

The limits _are_ applied.

So, this looks like some sort of race condition to me.

I tried to get information on this on the kernel mailing list [1], but
either noone read it or at least no one replied. Maybe someone here can
shed some light and maybe even fix the issue, if it is an issue.

Need more information? Please ask for it. I don't know what else to
supply at this point.

My current lab is built by:
OpenSuSE 11.3 64bit
Vanilla Kernel 2.6.37
libvirt 0.8.7
qemu-kvm 0.13.0
vm is started like this:
/usr/bin/qemu-kvm -M pc-0.12 -enable-kvm -m 2048 -smp
2,sockets=2,cores=1,threads=1 -name cliff -uuid
a8247e1e-e3d2-d0fc-c5e5-47a173c3e460 -nodefconfig -nodefaults -chardev
socket,id=monitor,path=/var/lib/libvirt/qemu/cliff.monitor,server,nowait
-mon chardev=monitor,mode=readline -rtc base=utc -boot c -device
lsi,id=scsi0,bus=pci.0,addr=0x6 -drive
file=/dev/vdisks/cliff,if=none,id=drive-virtio-disk0,boot=on,format=raw
-device
virtio-blk-pci,bus=pci.0,addr=0x4,drive=drive-virtio-disk0,id=virtio-disk0
-drive
file=/root/openSUSE-11.3-NET-x86_64.iso,if=none,media=cdrom,id=drive-ide0-1-0,readonly=on,format=raw
-device ide-drive,bus=ide.1,unit=0,drive=drive-ide0-1-0,id=ide0-1-0
-drive file=/dev/vdisks/jason,if=none,id=drive-virtio-disk1,format=raw
-device
virtio-blk-pci,bus=pci.0,addr=0x7,drive=drive-virtio-disk1,id=virtio-disk1
-drive file=/dev/vdisks/rob,if=none,id=drive-ide0-0-0,format=raw -device
ide-drive,bus=ide.0,unit=0,drive=drive-ide0-0-0,id=ide0-0-0 -drive
file=/dev/vdisks/james,if=none,id=drive-scsi0-0-0,format=raw -device
scsi-disk,bus=scsi0.0,scsi-id=0,drive=drive-scsi0-0-0,id=scsi0-0-0
-netdev tap,id=hostnet0 -device
virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:37:84:e0,bus=pci.0,addr=0x5
-usb -vnc 127.0.0.1:0 -vga cirrus -device
virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x3

Regards
Dominik

[1]
http://help.lockergnome.com/linux/race-condition-net_cls-found-qemu-kvm-environment--ftopict529787.html
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Re: [libvirt] cgroup limits only affect kvm guest under certain conditions

2011-01-06 Thread Dominik Klein 
 Did you just echo the main qemu-kvm PID, or did you also
 add the PIDs of every thread too ? From this description
 of the problem, I'd guess you've only confined the main
 process thread and thus the I/O  VCPU threads are not
 confined.

That was indeed correct. I was mislead by the fact that no child
_processes_ were shown in ps.

Once I added /proc/qemu-pid/tasks/* to tasks, it worked even when
libvirt started the process.

Thank you very much!
Dominik
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Re: cgroup limits only affect kvm guest under certain conditions

2011-01-06 Thread Dominik Klein 
 qemu consists of several threads. Cgroup works per thread now.
 Could you double check all threads for qemu are in a cgroup ?
 I think you have to write all thread-ID to tasks file when you
 move qemu after starting it.

As stated yesterday: Yes, that was the problem. Works as expected now,
thanks.

Dominik
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