On Sun, Oct 16, 2011 at 9:23 AM, Avi Kivity <avi@xxxxxxxxxx> wrote: > On 10/13/2011 02:51 AM, Jorge Lucangeli Obes wrote: >> On Wed, Oct 12, 2011 at 3:52 PM, Jorge Lucangeli Obes >> <jorgelo@xxxxxxxxxxxx> wrote: >> > On Wed, Oct 12, 2011 at 12:55 PM, Alexander Graf <agraf@xxxxxxx> wrote: >> >> >> >> On 12.10.2011, at 20:49, Jorge Lucangeli Obes wrote: >> >> >> >>> Hi all, >> >>> >> >>> I'm working on Chromium OS development. We have a pretty elaborate >> >>> chroot inside of which we carry out all development. We use KVM to >> >>> launch Chromium OS builds inside a VM for testing. Turns out that for >> >>> some reason, when QEMU is launched from inside the chroot, KVM itself >> >>> seems not to be used. The VM is extremely slow. >> >>> >> >>> Is this known/expected? QEMU is installed inside the chroot, the KVM >> >>> modules are loaded, the /dev/kvm device is present and accesible. Any >> >>> ideas on how to debug this? >> >> >> >> The first obvious idea I'd have here would be to strace the qemu process and check what happens when it opens /dev/kvm :) >> >> Resending since original attachment was too large. >> >> > That's what I thought. I did a test run under strace. I'm attaching >> > the list of syscalls from the call to 'open(/dev/kvm)' to the first >> > successful 'ioctl(KVM_RUN)'. /dev/kvm seems to be opened correctly, a >> > VCPU is created, and then that VCPU is used with KVM_RUN. After the >> > first call to 'ioctl(KVM_RUN)', there are long lists of more KVM_RUN >> > calls, separated by brief groups of other calls. So, IIUC, KVM seems >> > to be used, and seems to be "working", but the VM is one order of >> > magnitude slower anyways. >> > >> > Any ideas? >> > > What do top/vmstat/kvm_stat say? I'm attaching the output of the three commands during a test run launched form inside the chroot, which was slow as usual. I didn't see anything too weird on top/vmstat, though I found it odd that once the VM had booted Chromium OS, QEMU still ate 100% of one core. vmstat didn't show anything strange, QEMU taking up the memory it's supposed to. What I don't quite know how to interpret is the output of kvm_stat, hence the attachment. The host is a Xeon X5650, 6c12t. Kernel is 2.6.32, QEMU in the chroot is 0.12.5. Thanks for the help Avi. Cheers, Jorge
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kvm_stat_out
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vmstat_out
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