Re: Tracing kvm: kvm_entry and kvm_exit

[David Ahern <dsahern@gmail.com>]

On 3/3/13 11:15 PM, Mohamad Gebai wrote:
>> host kernel version?
> 3.8 compiled from perf-kvm-live-3.8

I made no changes to the kernel side so essentially you are running v3.8 
unmodified.

>> guest kernel?
> 3.8.1
>> qemu-kvm command line? (leave out the disk and network arguments -- just
>> the rest)
> Actually using virt-manager for this but here's the most relevant part of the
> qemu-kvm command line:
> /usr/bin/qemu-kvm -name debian_test -S -M pc-1.2 -enable-kvm -m 1024 -smp
> 1,sockets=1,cores=1,threads=1

ok, I take that to mean qemu-kvm 1.2.

> Actually qemu-kvm is launched first, then perf kvm is launched right after,
> before the bootloader of the VM using this command line:
> perf kvm stat -p <vm-pid> -e kvmmmu:*

I have not been able to reproduce it. Host kernel is v3.8, guest kernel 
is 3.8.1-201.fc18.x86_64 (Fedora 18, latest kernel). Host CPU: Intel(R) 
Xeon(R) CPU E5540  @ 2.53GHz.

qemu-kvm version is 1.2. Relevant command line (launched manually)

/usr/local/qemu-kvm/1.2/bin/qemu-system-x86_64 -m 4096 -smp 
1,sockets=1,cores=1,threads=1  -S -M pc-1.2

That starts the VM with paused vcpus. Then launch perf-kvm-stat:

perf kvm stat -p $(vm-status -b f18) -e kvmmmu:*

VM boots just fine.

When I get some time I can try qemu versions 1.3 and 1.4 to see if it 
makes a difference. Any output from the VM or host dmesg? What if you 
start qemu manually?

David