[Qemu-discuss] Multiple Guest performance issue

[Kevin Carpenter]

Hi all -

I'm having a Linux 3.5.4 KVM host with (4) Linux 3.5.4 KVM guest. 
Individually, the guest run fine, but if I load any one of them the 
others basically go to sleep.

I am not overloading memory... in fact its underutilized with zero swap 
activity.

Relevant parts of my local.start:

echo "Enabling KSM"
echo "1" >/sys/kernel/mm/ksm/run

echo "Setting up CGroup for QEMU"
mkdir /dev/cgroup
mount -t cgroup -o devices,cpu,memory none /dev/cgroup

echo "Starting up LAMP KVM"
cd /kvm

qemu-kvm -net nic,model=virtio -net tap,ifname=tap1,script=no -drive 
file=/dev/vg/lamp_vm,if=virtio -curses -daemonize -m 2g -smp 2 -runas 
kvm -name lampvm,process=lamp-kvm -cpu host

echo "Starting up Inbound Mail KVM"
cd /kvm

qemu-kvm -net nic,model=virtio -net tap,ifname=tap2,script=no -drive 
file=/dev/vg/mail_vm,if=virtio -curses -daemonize -m 1g -smp 1 -runas 
postmaster -name mailvm,process=mail-kvm -cpu host

echo "Starting up Outbound Mail KVM"
cd /kvm

qemu-kvm -net nic,model=virtio -net tap,ifname=tap3,script=no -drive 
file=/dev/vg/smtp_vm,if=virtio -curses -daemonize -m 1g -smp 1 -runas 
postmaster -name smtpvm,process=smtp-kvm -cpu host


#echo "Starting up DCIM KVM"
#cd /kvm

#nice -n 9 qemu-kvm -net nic,model=virtio -net 
tap,ifname=tap4,script=no  -drive file=/dev/vg/dcim_vm,if=virtio -curses 
-daemonize -m 2g -smp 2 -runas kvm -name dcimvm,process=dcim-kvm

echo "Starting up BOINC KVM"
cd /kvm
nice -n 19 qemu-kvm -net nic,model=virtio -net 
tap,ifname=tap0,script=no  -drive file=boinc.img,if=virtio -curses 
-daemonize -m 1g -smp 6 -runas boinc_vm -name boincvm,process=boinc-kvm 
-cpu host

Performance problems occur with or without the BOINC cpu-sucker running.

Does anybody see anything I'm doing seriously wrong?

Host has virtualization enabled with AMD support (its running on a 6-way 
AMD) and acceleration for virtio net.
Guests all have paravirtualized guest support wtih KVM paravirtualized 
clock, KVM Guest suppoirt, and paravirtualization layer for spinlocks.

The slow system behaves almost like its swapped, or locked, out. 30-45 
second password prompts, crawling command line prompts, until it "wakes 
up", then everything is fine (until its not again).

Appreciate any suggestions.

Kevin