Virtualization of Perf Counters

This page is mostly a placeholder with info gathered while doing VM perf counter work. It's not meant to be exhaustive, just notes I want to jot down so I don't forget.

KVM

As of Linux 3.3 KVM supports perf counters in the guest. You also need a recent enough Qemu (as of April 2012 that means a git snapshot). Aggregate counts are supported, although overflow interrupts don't seem to be.

I'm using a Debian Unstable disk image. with the command line:

./qemu/bin/qemu-system-x86_64 -cpu host -drive if=virtio,aio=native,file=vmw5.qcow2 -m 512 -nographic --enable-kvm

It works on a core2 machine. On sandybridge I have to boot the kernel with the "nox2apic" option, as it crashes on boot otherwise.

To get the serial console to work at boot I need to add the following to the /etc/default/grub file and then run update-grub:

GRUB_TERMINAL=serial
GRUB_SERIAL_COMMAND="serial --unit=0 --speed=115200 --word=8 --parity=no --stop=1"
GRUB_CMDLINE_LINUX_DEFAULT="nox2apic"
GRUB_CMDLINE_LINUX="text console=tty0 console=ttyS0,115200n8"

Xen

Xen has work on perf-counters done too. At one point I had Xenoprof, which was oprofile for Xen, going on a laptop but I lost the disk image.

VMware

Doesn't currently support perf counters in guest, but the next version might.

Host Measurement

You can also use perf counters to measure a guest from outside, in the host. See the perf tool's "kvm" options of vmkperf on VMware.

Back to unofficial perf_event pages